小专题八一元一次方程的解法

1、小专题（八）一元一次方程的解法1解下列方程：(1)5x 7x = 16X 2+ 2;(2心+ x + 2x= 140;(3)56 8x = 11 + x;(4)4x+ 1 = 5 + 3x.2.解下列方程：(1)4x 3(20 2x) = 10;(2)3(2x + 5) = 2(4x + 3) 3;(3)3x 7(x 1) = 3-2(x + 3).3. 解下列方程:紧17 20x31；2x 1丁2 (x+ 3)532 (x 7)2x32x 110x + 1 丁 =2x+ 12(x 5)=4.解下列方程:(1)0.1 2x0.32x 1.6 3x _ 31x + 8(2)0.30.6 =35.

2、解方程：3|x| 5=七+ 1.6.解下列方程:/八112亍x + 2=25.9x7；(2)y -(3)278(x 3) 463(6 2x) 888(7x 21)= 0;3 2 x(4)刃3(41)2 x=2；(5)x 3【x 3(x 9) = 9(x 9).参考答案7411. (1) 2x= 8 + 2, x = 5.(2)2x = 140, x= 40.(3) 8x x= 11 56, 9x= 45, x= 5.歹衣=5 1 , x= 4.2. (1)4x 60 + 6x = 10 , 4x + 6x = 60 + 10, 10x = 70, x = 7.(2)6x + 15= 8x +

3、6 3, 6x 8x= 15+ 6 3, 2x = 12, x = 6.(3)3x 7x + 7= 3 2x 6, 3x 7x + 2x = 3 6 7, 2x = 10, x = 5.143. (1)30x 7(17 20x) = 21, 30x 119+ 140x= 21 , 30x+ 140x= 119+ 21, 170x= 140, x= .(2)4(2x 1) 3(2x 3) =12, 8x 4 6x+ 9= 12, 8x 6x = 4 9+ 12, 2x = 7, x = |.(3)12(x + 3)= 45x 20(x 7), 12x + 36= 45x 20x + 140 ,

4、12x 45x + 20x = 36+ 140 , 13x = 104 , x = 8.(4)2(2x 1) (10x + 1) = 3(2x + 1) 6 , 4x 2 10x 1= 6x+ 3 6, 12x = 0 , x = 0.(5)6(x + 4) 30(x 5) = 10(x + 3) 15(x 2) , 6x + 24 30x + 150 = 10x + 30 15x + 30 , 6x 30x 10x + 15x = 30 + 30 24 150 , 19x = 114 , x = 6.1 20x100x4. (1)法一：原方程整理，得一3 = 1 + Q .去分母，得5(1

5、20x) = 15+ 100x.去括号,得5 100x = 15+ 100x.移项， 得100x 100x = 15 5.合并同类项，得 200x = 10.系数化为 1,得 x = 0.05.法二：去分母，得 0.15(0.1 2x)= 0.045 + 0.3x.去括号,得 0.015 0.3x= 0.045+ 0.3x.移项，得0.3x 0.3x = 0.045 0.015.合并同类项，得0.6x = 0.03.20x16 30x31x + 8系数化为 1,得 x = 0.05.(2)可6= 产,40x (16 30x) = 2(31x+ 8) , 40x 16 + 30x= 62x + 16 , 40x363+ 30x 62x = 16+ 16 , 8x = 32 , x = 4.5.6|x| 10= |x| 2 + 2 , 5|x|= 10 , |x|= 2 , x= 2 或一2.112526.(1)x 9x = 7 7 , x = 1.(2)y 0.5(y 1) = 2 0.2(y + 2) , y 0.5y + 0.5 = 2 0.2y 0.4 , 0.7y = 1.1 , y = 11xy.(3)278(x 3) + 463X 2(x 3) 888 X 7(x 3) = 0 , (278 + 463X