（全国版）中考数学复习提分专练01实数混合运算与代数式的化简求值.docx

提分专练(一)实数混合运算与代数式的化简求值|类型1|实数的运算1.2018陕西 计算:(-3)(-6)+|2-1|+(5-2)0.2.2019南充计算:(1-)0+|2-3|-12+12-1.3.2019广安计算:(-1)4-|1-3|+6tan30-(3-27)0.4.2019遂宁计算:(-1)2019+(-2)-2+(3.14-)0-4cos30+|2-12|.|类型2|整式的化简求值5.2019常州如果a-b-2=0,那么代数式1+2a-2b的值是.6.2019常德若x2+x=1,则3x4+3x3+3x+1的值为.7.2019淮安计算:ab(3a-2b)+2ab2.8.2019吉林 先化简,再求值:(a-1)2+a(a+2),其中a=2.9.若x+y=3,且(x+3)(y+3)=20.(1)求xy的值;(2)求x2+3xy+y2的值.|类型3|分式的化简求值10.2019淮安先化简,再求值:a2-4a1-2a,其中a=5.11.2019黄石先化简,再求值:3x+2+x-2x2-2x+1x+2,其中|x|=2.12.2019菏泽先化简,再求值:1x-y2yx+y-11y2-x2,其中x=y+2019.13.2019天水先化简,再求值:xx2+x-1x2-1x2+2x+1,其中x的值从不等式组-x1,2x-15的整数解中选取.14.2019荆门先化简,再求值:a+ba-b22a-2b3a+3b-4a2a2-b23ab,其中a=3,b=2.15.2019遂宁先化简,再求值:a2-2ab+b2a2-b2a2-aba-2a+b,其中a,b满足(a-2)2+b+1=0.【参考答案】1.解:(-3)(-6)+|2-1|+(5-2)0=18+2-1+1=32+2=42.2.解:原式=1+3-2-23+2=1-3.3.解:原式=1-(3-1)+633-1=1-3+1+23-1=1+3.4.解:(-1)2019+(-2)-2+(3.14-)0-4cos30+|2-12|=-1+14+1-432+23-2=-74.5.56.4解析3x4+3x3+3x+1=3x2(x2+x)+3x+1=3x2+3x+1=3(x2+x)+1=4.7.解:ab(3a-2b)+2ab2=3a2b-2ab2+2ab2=3a2b.8.解:原式=a2-2a+1+a2+2a=2a2+1,当a=2时,原式=2(2)2+1=22+1=5.9.解:(1)(x+3)(y+3)=20,xy+3x+3y+9=20,即xy+3(x+y)=11.将x+y=3代入得xy+9=11,xy=2.(2)当xy=2,x+y=3时,原式=(x+y)2+xy=32+2=9+2=11.10.解:a2-4a1-2a=a2-4aa-2a=a2-4aaa-2=(a+2)(a-2)aaa-2=a+2.当a=5时,原式=5+2=7.11.解:原式=x2-1x+2(x-1)2x+2=(x+1)(x-1)x+2x+2(x-1)2=x+1x-1.|x|=2,x=2,由分式有意义的条件可知:x=2,原式=3.12.解:1x-y2yx+y-11y2-x2=1x-y2y-(x+y)x+y(y+x)(y-x)=-(2y-x-y)=x-y.x=y+2019,原式=y+2019-y=2019.13.解:原式=x-x2-xx(x+1)x+1x-1=-xx+1x+1x-1=x1-x.解不等式组-x1,2x-15得-1x3,则不等式组的整数解为-1,0,1,2.x1,x0,x=2,原式=21-2=-2.14.解:原式=2(a+b)3(a-b)-4ab3(a+b)(a-b)=2(a+b)2-4ab3(a+b)(a-b)=2(a2+b2)3(a+b)(a-b).当a=3,b=2时,原式=2(3+2)3(3+2)(3-2)=103.15.解