2026七年级数学整式计算与化简求值专项训练100题-含解析

七年级数学专项训练｜整式计算与化简求值姓名：__________班级：__________日期：__________2026七年级数学整式计算与化简求值专项训练100题_含解析原创专项训练｜100题完整编号｜配答题卡、答案解析、错题复盘与二刷安排项目说明适用对象七年级上、下学期学生；适用于整式初学、期初诊断、单元巩固、暑假后半段收心训练和开学前基础回补。使用场景可用于45分钟课堂训练、60分钟专项测评、家庭限时练习、错题二刷、教师讲评与家长检查反馈。资料构成本资料包含5类共100题：合并同类项20题、去括号20题、整式加减20题、化简求值20题、易错题20题；配套答题卡、参考答案、逐题解析、易错点清单、错题统计表、二刷计划表和讲评记录表。三步使用方法第一步按类别限时完成并在答题卡记录；第二步对照答案解析订正，标出符号、括号、同类项、代入四类错误；第三步根据错题编号完成二刷计划，并由教师或家长进行讲评记录。训练建议：基础较弱学生可分5天完成，每天20题；基础稳定学生可用2次完成，第一次做1—60题，第二次做61—100题；讲评时优先处理“括号前负号、分数系数、负数代入、同类项识别”四类问题。一、训练结构与评分建议题号范围训练模块题量建议用时核心能力评分建议1—20合并同类项20题15分钟识别同类项，准确合并系数每题1分，共20分21—40去括号20题18分钟掌握括号前系数与符号变化每题1分，共20分41—60整式加减20题20分钟整式整体相加减与分组整理每题1分，共20分61—80化简求值20题25分钟先化简再代入，规范书写每题1.5分，共30分81—100易错题20题25分钟处理符号、分数、嵌套括号与负数代入每题1.5分，共30分合计整式计算专项100题约103分钟计算正确率、过程规范性、错因归类满分120分，可按班级实际折算二、学生答题卡与得分登记使用说明：每题先在训练区写过程，再把最终结果填入答题卡；订正时在“错因”栏填写符号错误、括号错误、同类项错误、代入错误或书写不规范。1—20合并同类项21—40去括号41—60整式加减61—80化简求值81—100易错题1.____________21.____________41.____________61.____________81.____________2.____________22.____________42.____________62.____________82.____________3.____________23.____________43.____________63.____________83.____________4.____________24.____________44.____________64.____________84.____________5.____________25.____________45.____________65.____________85.____________6.____________26.____________46.____________66.____________86.____________7.____________27.____________47.____________67.____________87.____________8.____________28.____________48.____________68.____________88.____________9.____________29.____________49.____________69.____________89.____________10.____________30.____________50.____________70.____________90.____________11.____________31.____________51.____________71.____________91.____________12.____________32.____________52.____________72.____________92.____________13.____________33.____________53.____________73.____________93.____________14.____________34.____________54.____________74.____________94.____________15.____________35.____________55.____________75.____________95.____________16.____________36.____________56.____________76.____________96.____________17.____________37.____________57.____________77.____________97.____________18.____________38.____________58.____________78.____________98.____________19.____________39.____________59.____________79.____________99.____________20.____________40.____________60.____________80.____________100.____________模块完成题数正确题数得分主要错因订正完成复核人合并同类项20________________________□是□否____去括号20________________________□是□否____整式加减20________________________□是□否____化简求值20________________________□是□否____易错题20________________________□是□否____填写样例201717括号前负号☑是□否家长三、专项训练100题合并同类项1—20题：先找同类项，再把系数相加减，结果按同类项类别整理。001.化简：3a+5a-2a作答区：____________________________________________________________过程补充：____________________________________________________________002.化简：7x-3x+2x作答区：____________________________________________________________过程补充：____________________________________________________________003.化简：4m+6n-2m+3n作答区：____________________________________________________________过程补充：____________________________________________________________004.化简：5a²-2a²+7a²作答区：____________________________________________________________过程补充：____________________________________________________________005.化简：8x²+3x-5x²+4x作答区：____________________________________________________________过程补充：____________________________________________________________006.化简：6ab-2ab+5ab作答区：____________________________________________________________过程补充：____________________________________________________________007.化简：9xy-4x+3xy+6x作答区：____________________________________________________________过程补充：____________________________________________________________008.化简：2a+3b+4a-5b作答区：____________________________________________________________过程补充：____________________________________________________________009.化简：-3x²+8x²-2x²作答区：____________________________________________________________过程补充：____________________________________________________________010.化简：4m²n+2mn²-3m²n+5mn²作答区：____________________________________________________________过程补充：____________________________________________________________011.化简：0.5a+1.5a-0.8a作答区：____________________________________________________________过程补充：____________________________________________________________012.化简：(2/3)x+(1/6)x-(1/2)x作答区：____________________________________________________________过程补充：____________________________________________________________013.化简：5a-3b-2a+7b-4a作答区：____________________________________________________________过程补充：____________________________________________________________014.化简：3x²y-xy²+2x²y+4xy²作答区：____________________________________________________________过程补充：____________________________________________________________015.化简：-6p+4n+9p-7n作答区：____________________________________________________________过程补充：____________________________________________________________016.化简：a²+2a+3a²-5a+6作答区：____________________________________________________________过程补充：____________________________________________________________017.化简：10xy-3y+2xy+8y-5xy作答区：____________________________________________________________过程补充：____________________________________________________________018.化简：2x³-5x²+4x³+6x²作答区：____________________________________________________________过程补充：____________________________________________________________019.化简：-a+2b+3a-4b+5a作答区：____________________________________________________________过程补充：____________________________________________________________020.化简：4x²-2xy+6xy-7x²+3作答区：____________________________________________________________过程补充：____________________________________________________________去括号21—40题：括号前是正数时各项符号不变；括号前是负数或负系数时，括号内每一项都要变号或相乘。021.化简：2(x+3)作答区：____________________________________________________________过程补充：____________________________________________________________022.化简：-3(a-2b)作答区：____________________________________________________________过程补充：____________________________________________________________023.化简：4(2x-5)-3x作答区：____________________________________________________________过程补充：____________________________________________________________024.化简：5a-(2a-3)作答区：____________________________________________________________过程补充：____________________________________________________________025.化简：3x+2(x-4)作答区：____________________________________________________________过程补充：____________________________________________________________026.化简：7m-3(2m+n)作答区：____________________________________________________________过程补充：____________________________________________________________027.化简：-(a+b-c)作答区：____________________________________________________________过程补充：____________________________________________________________028.化简：2[3x-(x-5)]作答区：____________________________________________________________过程补充：____________________________________________________________029.化简：3(a-2b)-2(a+b)作答区：____________________________________________________________过程补充：____________________________________________________________030.化简：-2(x²-3x+1)作答区：____________________________________________________________过程补充：____________________________________________________________031.化简：4(1-2y)+5(y-3)作答区：____________________________________________________________过程补充：____________________________________________________________032.化简：6a-2(3a-4b)+b作答区：____________________________________________________________过程补充：____________________________________________________________033.化简：3x-[2x-(x-4)]作答区：____________________________________________________________过程补充：____________________________________________________________034.化简：5m-{2m-[m-(n-1)]}作答区：____________________________________________________________过程补充：____________________________________________________________035.化简：2(x+y)-3(x-y)作答区：____________________________________________________________过程补充：____________________________________________________________036.化简：-0.5(4a-6b)+2a作答区：____________________________________________________________过程补充：____________________________________________________________037.化简：(1/3)(6x-9)-2x作答区：____________________________________________________________过程补充：____________________________________________________________038.化简：a-2[3a-(a-4)]作答区：____________________________________________________________过程补充：____________________________________________________________039.化简：3(2x²-x)-2(x²+3x)作答区：____________________________________________________________过程补充：____________________________________________________________040.化简：-(2a-b)+3(a-2b)作答区：____________________________________________________________过程补充：____________________________________________________________整式加减41—60题：把每个整式看作整体，先去括号，再合并同类项。041.化简：(3x²-2x+5)+(x²+4x-7)作答区：____________________________________________________________过程补充：____________________________________________________________042.化简：(5a-3b)-(2a+4b)作答区：____________________________________________________________过程补充：____________________________________________________________043.化简：(2m²+m-1)+(3m²-4m+6)作答区：____________________________________________________________过程补充：____________________________________________________________044.化简：(7x-2y+3)-(4x+5y-6)作答区：____________________________________________________________过程补充：____________________________________________________________045.化简：(a²+2ab+b²)-(a²-2ab+b²)作答区：____________________________________________________________过程补充：____________________________________________________________046.化简：(6x²-3xy+y²)+(-2x²+5xy-4y²)作答区：____________________________________________________________过程补充：____________________________________________________________047.化简：2(3a-b)+(a+4b)作答区：____________________________________________________________过程补充：____________________________________________________________048.化简：3(x²-x+1)-(2x²+3x-5)作答区：____________________________________________________________过程补充：____________________________________________________________049.化简：(4p-3n+2)-(p+n-5)作答区：____________________________________________________________过程补充：____________________________________________________________050.化简：5(a-b)-2(a+b)+3b作答区：____________________________________________________________过程补充：____________________________________________________________051.化简：(2x²+3x)-(x²-5x+4)+(6-2x)作答区：____________________________________________________________过程补充：____________________________________________________________052.化简：(m²-2mn+n²)+(2mn-3n²)作答区：____________________________________________________________过程补充：____________________________________________________________053.化简：4x-[3x-(2x-1)]作答区：____________________________________________________________过程补充：____________________________________________________________054.化简：(8a-5)-(3a+2)+(a-4)作答区：____________________________________________________________过程补充：____________________________________________________________055.化简：2(x+y+1)-3(x-y-2)作答区：____________________________________________________________过程补充：____________________________________________________________056.化简：(3a²-2a+1)-2(a²+a-3)作答区：____________________________________________________________过程补充：____________________________________________________________057.化简：-[(x²-3x)+(-2x²+x-1)]作答区：____________________________________________________________过程补充：____________________________________________________________058.化简：(5xy-2x+3y)-(-xy+4x-y)作答区：____________________________________________________________过程补充：____________________________________________________________059.化简：3a-(2a-b)+2(a-3b)作答区：____________________________________________________________过程补充：____________________________________________________________060.化简：(x²+2x+3)+(2x²-x-4)-(3x²+x-1)作答区：____________________________________________________________过程补充：____________________________________________________________化简求值61—80题：必须先化简后代入；代入负数、分数时要加括号。061.先化简，再求值：2x+3x-5，其中x=4作答区：____________________________________________________________过程补充：____________________________________________________________062.先化简，再求值：3a-2b+a+5b，其中a=2，b=-1作答区：____________________________________________________________过程补充：____________________________________________________________063.先化简，再求值：2(x+3)-x，其中x=-2作答区：____________________________________________________________过程补充：____________________________________________________________064.先化简，再求值：5m-2(3m-1)，其中m=3作答区：____________________________________________________________过程补充：____________________________________________________________065.先化简，再求值：a²+3a²-2a，其中a=-1作答区：____________________________________________________________过程补充：____________________________________________________________066.先化简，再求值：4x²-2x+3x²+x，其中x=2作答区：____________________________________________________________过程补充：____________________________________________________________067.先化简，再求值：3(a-b)-2(a+b)，其中a=5，b=2作答区：____________________________________________________________过程补充：____________________________________________________________068.先化简，再求值：(2x²-x+1)-(x²+2x-4)，其中x=-1作答区：____________________________________________________________过程补充：____________________________________________________________069.先化简，再求值：6xy-2x+3xy+5x，其中x=1，y=-2作答区：____________________________________________________________过程补充：____________________________________________________________070.先化简，再求值：2[3a-(a-4)]，其中a=-3作答区：____________________________________________________________过程补充：____________________________________________________________071.先化简，再求值：m²-2mn+n²，其中m=3，n=1作答区：____________________________________________________________过程补充：____________________________________________________________072.先化简，再求值：(x+y)-(2x-y)+3x，其中x=-2，y=4作答区：____________________________________________________________过程补充：____________________________________________________________073.先化简，再求值：(1/2)a+(3/2)a-a，其中a=6作答区：____________________________________________________________过程补充：____________________________________________________________074.先化简，再求值：3x-[x-2(x-1)]，其中x=5作答区：____________________________________________________________过程补充：____________________________________________________________075.先化简，再求值：2a²b-3ab²+ab²，其中a=-1，b=2作答区：____________________________________________________________过程补充：____________________________________________________________076.先化简，再求值：5-(2x-3)+4x，其中x=-4作答区：____________________________________________________________过程补充：____________________________________________________________077.先化简，再求值：3(x²-2x)+2(x²+x)，其中x=1/2作答区：____________________________________________________________过程补充：____________________________________________________________078.先化简，再求值：2(a+b)-[a-(b-1)]，其中a=0，b=-3作答区：____________________________________________________________过程补充：____________________________________________________________079.先化简，再求值：7p-3(p-2n)+2n，其中p=-2，n=1作答区：____________________________________________________________过程补充：____________________________________________________________080.先化简，再求值：(x²+xy)-(xy-y²)+2y²，其中x=2，y=-1作答区：____________________________________________________________过程补充：____________________________________________________________易错题81—100题：重点检查符号、分数、嵌套括号、平方和负数代入。081.化简：-(x-2)+3(x+1)作答区：____________________________________________________________过程补充：____________________________________________________________082.化简：2a-[-3a+(a-4)]作答区：____________________________________________________________过程补充：____________________________________________________________083.化简：3x²-2x(x-1)作答区：____________________________________________________________过程补充：____________________________________________________________084.化简：-2(a-b)-3(b-a)作答区：____________________________________________________________过程补充：____________________________________________________________085.化简：0.2x+0.3x-1/2x作答区：____________________________________________________________过程补充：____________________________________________________________086.化简：(1/4)(8m-4)-2(m-1)作答区：____________________________________________________________过程补充：____________________________________________________________087.化简：3a-[2a-(a-b)]作答区：____________________________________________________________过程补充：____________________________________________________________088.化简：5x-2{3x-[x-(2-x)]}作答区：____________________________________________________________过程补充：____________________________________________________________089.化简：(a²+2a)-(3a²-a)+2a²作答区：____________________________________________________________过程补充：____________________________________________________________090.化简：2xy-3x+4xy+3x-xy作答区：____________________________________________________________过程补充：____________________________________________________________091.先化简，再求值：2x-(3x-4)+x，其中x=-3作答区：____________________________________________________________过程补充：____________________________________________________________092.先化简，再求值：a²-2a+1，其中a=-2作答区：____________________________________________________________过程补充：____________________________________________________________093.化简：3(2x-1)-2(3x+1)作答区：____________________________________________________________过程补充：____________________________________________________________094.化简：-(2m-n)+(-m+3n)作答区：____________________________________________________________过程补充：____________________________________________________________095.化简：4a-2[a-3(a-1)]作答区：____________________________________________________________过程补充：____________________________________________________________096.化简：(x²-xy+y²)-(2x²+xy-y²)作答区：____________________________________________________________过程补充：____________________________________________________________097.先化简，再求值：(1/3)x+(1/2)x-(5/6)x，其中x=12作答区：____________________________________________________________过程补充：____________________________________________________________098.化简：2(a-2b)-[3a-(b-1)]作答区：____________________________________________________________过程补充：____________________________________________________________099.化简：-x²+2x²-3x+x²+5x作答区：____________________________________________________________过程补充：____________________________________________________________100.先化简，再求值：2(x-y)-3(y-x)，其中x=1，y=-2作答区：____________________________________________________________过程补充：____________________________________________________________

四、参考答案与逐题解析核对建议：只看答案不算订正完成。每道错题至少写出“错在何处、正确步骤、同类题再练编号”三项。合并同类项答案解析题号答案解析0016a同类项字母部分完全相同，把对应系数相加减，原式=6a。0026x同类项字母部分完全相同，把对应系数相加减，原式=6x。0032m+9n同类项字母部分完全相同，把对应系数相加减，原式=2m+9n。00410a²同类项字母部分完全相同，把对应系数相加减，原式=10a²。0053x²+7x同类项字母部分完全相同，把对应系数相加减，原式=3x²+7x。0069ab同类项字母部分完全相同，把对应系数相加减，原式=9ab。00712xy+2x同类项字母部分完全相同，把对应系数相加减，原式=12xy+2x。0086a-2b同类项字母部分完全相同，把对应系数相加减，原式=6a-2b。0093x²同类项字母部分完全相同，把对应系数相加减，原式=3x²。010m²n+7mn²同类项字母部分完全相同，把对应系数相加减，原式=m²n+7mn²。0116a/5同类项字母部分完全相同，把对应系数相加减，原式=6a/5。012x/3同类项字母部分完全相同，把对应系数相加减，原式=x/3。013-a+4b同类项字母部分完全相同，把对应系数相加减，原式=-a+4b。0145x²y+3xy²同类项字母部分完全相同，把对应系数相加减，原式=5x²y+3xy²。015-3n+3p同类项字母部分完全相同，把对应系数相加减，原式=-3n+3p。0164a²-3a+6同类项字母部分完全相同，把对应系数相加减，原式=4a²-3a+6。0177xy+5y同类项字母部分完全相同，把对应系数相加减，原式=7xy+5y。0186x³+x²同类项字母部分完全相同，把对应系数相加减，原式=6x³+x²。0197a-2b同类项字母部分完全相同，把对应系数相加减，原式=7a-2b。020-3x²+4xy+3同类项字母部分完全相同，把对应系数相加减，原式=-3x²+4xy+3。去括号答案解析题号答案解析0212x+6先按括号前的系数和符号逐项展开，再合并同类项，原式=2x+6。022-3a+6b先按括号前的系数和符号逐项展开，再合并同类项，原式=-3a+6b。0235x-20先按括号前的系数和符号逐项展开，再合并同类项，原式=5x-20。0243a+3先按括号前的系数和符号逐项展开，再合并同类项，原式=3a+3。0255x-8先按括号前的系数和符号逐项展开，再合并同类项，原式=5x-8。026m-3n先按括号前的系数和符号逐项展开，再合并同类项，原式=m-3n。027-a-b+c先按括号前的系数和符号逐项展开，再合并同类项，原式=-a-b+c。0284x+10先按括号前的系数和符号逐项展开，再合并同类项，原式=4x+10。029a-8b先按括号前的系数和符号逐项展开，再合并同类项，原式=a-8b。030-2x²+6x-2先按括号前的系数和符号逐项展开，再合并同类项，原式=-2x²+6x-2。031-3y-11先按括号前的系数和符号逐项展开，再合并同类项，原式=-3y-11。0329b先按括号前的系数和符号逐项展开，再合并同类项，原式=9b。0332x-4先按括号前的系数和符号逐项展开，再合并同类项，原式=2x-4。0344m-n+1先按括号前的系数和符号逐项展开，再合并同类项，原式=4m-n+1。035-x+5y先按括号前的系数和符号逐项展开，再合并同类项，原式=-x+5y。0363b先按括号前的系数和符号逐项展开，再合并同类项，原式=3b。037-3先按括号前的系数和符号逐项展开，再合并同类项，原式=-3。038-3a-8先按括号前的系数和符号逐项展开，再合并同类项，原式=-3a-8。0394x²-9x先按括号前的系数和符号逐项展开，再合并同类项，原式=4x²-9x。040a-5b先按括号前的系数和符号逐项展开，再合并同类项，原式=a-5b。整式加减答案解析题号答案解析0414x²+2x-2把括号内整式作为整体处理，去括号后合并同类项，原式=4x²+2x-2。0423a-7b把括号内整式作为整体处理，去括号后合并同类项，原式=3a-7b。0435m²-3m+5把括号内整式作为整体处理，去括号后合并同类项，原式=5m²-3m+5。0443x-7y+9把括号内整式作为整体处理，去括号后合并同类项，原式=3x-7y+9。0454ab把括号内整式作为整体处理，去括号后合并同类项，原式=4ab。0464x²+2xy-3y²把括号内整式作为整体处理，去括号后合并同类项，原式=4x²+2xy-3y²。0477a+2b把括号内整式作为整体处理，去括号后合并同类项，原式=7a+2b。048x²-6x+8把括号内整式作为整体处理，去括号后合并同类项，原式=x²-6x+8。049-4n+3p+7把括号内整式作为整体处理，去括号后合并同类项，原式=-4n+3p+7。0503a-4b把括号内整式作为整体处理，去括号后合并同类项，原式=3a-4b。051x²+6x+2把括号内整式作为整体处理，去括号后合并同类项，原式=x²+6x+2。052m²-2n²把括号内整式作为整体处理，去括号后合并同类项，原式=m²-2n²。0533x-1把括号内整式作为整体处理，去括号后合并同类项，原式=3x-1。0546a-11把括号内整式作为整体处理，去括号后合并同类项，原式=6a-11。055-x+5y+8把括号内整式作为整体处理，去括号后合并同类项，原式=-x+5y+8。056a²-4a+7把括号内整式作为整体处理，去括号后合并同类项，原式=a²-4a+7。057x²+2x+1把括号内整式作为整体处理，去括号后合并同类项，原式=x²+2x+1。0586xy-6x+4y把括号内整式作为整体处理，去括号后合并同类项，原式=6xy-6x+4y。0593a-5b把括号内整式作为整体处理，去括号后合并同类项，原式=3a-5b。0600把括号内整式作为整体处理，去括号后合并同类项，原式=0。化简求值答案解析题号答案解析06115先去括号并合并同类项，原式=5x-5；代入x=4，得15。0625先去括号并合并同类项，原式=4a+3b；代入a=2，b=-1，得5。0634先去括号并合并同类项，原式=x+6；代入x=-2，得4。064-1先去括号并合并同类项，原式=-m+2；代入m=3，得-1。0656先去括号并合并同类项，原式=4a²-2a；代入a=-1，得6。06626先去括号并合并同类项，原式=7x²-x；代入x=2，得26。067-5先去括号并合并同类项，原式=a-5b；代入a=5，b=2，得-5。0689先去括号并合并同类项，原式=x²-3x+5；代入x=-1，得9。069-15先去括号并合并同类项，原式=9xy+3x；代入x=1，y=-2，得-15。070-4先去括号并合并同类项，原式=4a+8；代入a=-3，得-4。0714先去括号并合并同类项，原式=m²-2mn+n²；代入m=3，n=1，得4。0724先去括号并合并同类项，原式=2x+2y；代入x=-2，y=4，得4。0736先去括号并合并同类项，原式=a；代入a=6，得6。07418先去括号并合并同类项，原式=4x-2；代入x=5，得18。07512先去括号并合并同类项，原式=2a²b-2ab²；代入a=-1，b=2，得12。0760先去括号并合并同类项，原式=2x+8；代入x=-4，得0。077-3/4先去括号并合并同类项，原式=5x²-4x；代入x=1/2，得-3/4。078-10先去括号并合并同类项，原式=a+3b-1；代入a=0，b=-3，得-10。0790先去括号并合并同类项，原式=8n+4p；代入p=-2，n=1，得0。0807先去括号并合并同类项，原式=x²+3y²；代入x=2，y=-1，得7。易错题答案解析题号答案解析0812x+5先处理括号和符号，再按同类项合并，原式=2x+5。易错提醒：注意括号前负号要变号。0824a+4先处理括号和符号，再按同类项合并，原式=4a+4。易错提醒：中括号前是减号，去括号时整体变号。083x²+2x先处理括号和符号，再按同类项合并，原式=x²+2x。易错提醒：乘法分配到每一项，不能只乘第一项。084a-b先处理括号和符号，再按同类项合并，原式=a-b。易错提醒：b-a与a-b互为相反数。0850先处理括号和符号，再按同类项合并，原式=0。易错提醒：小数可先化成分数或统一到十分位。0861先处理括号和符号，再按同类项合并，原式=1。易错提醒：分数系数也要分别乘括号内每一项。0872a-b先处理括号和符号，再按同类项合并，原式=2a-b。易错提醒：逐层去括号，先处理最内层。0883x-4先处理括号和符号，再按同类项合并，原式=3x-4。易错提醒：多层括号要按由内到外的顺序。0893a先处理括号和符号，再按同类项合并，原式=3a。易错提醒：同类项要看字母和指数，不是只看字母。0905xy先处理括号和符号，再按同类项合并，原式=5xy。易错提醒：不同类项不能合并，抵消的项要写清。0914先去括号并合并同类项，原式=4；代入x=-3，得4。易错提醒：代入负数时要带括号。0929先去括号并合并同类项，原式=a²-2a+1；代入a=-2，得9。易错提醒：平方先算，负数平方为正。093-5先处理括号和符号，再按同类项合并，原式=-5。易错提醒：两处括号都要完整展开。094-3m+4n先处理括号和符号，再按同类项合并，原式=-3m+4n。易错提醒：负号后的2m和-n都要变号。0958a-6先处理括号和符号，再按同类项合并，原式=8a-6。易错提醒：括号嵌套时先确定每一层符号。096-x²-2xy+2y²先处理括号和符号，再按同类项合并，原式=-x²-2xy+2y²。易错提醒：减去整式时整式内各项均变号。0970先去括号并合并同类项，原式=0；代入x=12，得0。易错提醒：通分后再合并系数。098-a-3b-1先处理括号和符号，再按同类项合并，原式=-a-3b-1。易错提醒：中括号前负号影响所有项。0992x²+2x先处理括号和符号，再按同类项合并，原式