零五网 全部参考答案 启东中学作业本 2025年启东中学作业本七年级数学上册人教版 第32页解析答案
解方程:
(1)$4(2x+1)=-20$; (2)$3(2x-1)=5x+2$;
(3)$4x+2(5-x)=6$; (4)$4x-6=3(5-x)$;
(5)$2+x=-5(x-1)$; (6)$3x-2=2(4x-6)$;
(7)$2(x-1)-5=7x$; (8)$5x+2=3(x+2)$;
(9)$5(1+x)=2x-4$; (10)$3-(x+2)=5(x+1)$;
(11)$2(x-1)-2=4x$; (12)$4-3(2-x)=5x$.
答案:(1)x=-3 (2)x=5 (3)x=-2 (4)x=3 (5)x=$\frac{1}{2}$ (6)x=2 (7)x=-$\frac{7}{5}$ (8)x=2 (9)x=-3 (10)x=-$\frac{2}{3}$ (11)x=-2 (12)x=-1
解析:
(1)解:$4(2x + 1) = -20$
$8x + 4 = -20$
$8x = -24$
$x = -3$
(2)解:$3(2x - 1) = 5x + 2$
$6x - 3 = 5x + 2$
$6x - 5x = 2 + 3$
$x = 5$
(3)解:$4x + 2(5 - x) = 6$
$4x + 10 - 2x = 6$
$2x = 6 - 10$
$2x = -4$
$x = -2$
(4)解:$4x - 6 = 3(5 - x)$
$4x - 6 = 15 - 3x$
$4x + 3x = 15 + 6$
$7x = 21$
$x = 3$
(5)解:$2 + x = -5(x - 1)$
$2 + x = -5x + 5$
$x + 5x = 5 - 2$
$6x = 3$
$x = \frac{1}{2}$
(6)解:$3x - 2 = 2(4x - 6)$
$3x - 2 = 8x - 12$
$3x - 8x = -12 + 2$
$-5x = -10$
$x = 2$
(7)解:$2(x - 1) - 5 = 7x$
$2x - 2 - 5 = 7x$
$2x - 7x = 7$
$-5x = 7$
$x = -\frac{7}{5}$
(8)解:$5x + 2 = 3(x + 2)$
$5x + 2 = 3x + 6$
$5x - 3x = 6 - 2$
$2x = 4$
$x = 2$
(9)解:$5(1 + x) = 2x - 4$
$5 + 5x = 2x - 4$
$5x - 2x = -4 - 5$
$3x = -9$
$x = -3$
(10)解:$3 - (x + 2) = 5(x + 1)$
$3 - x - 2 = 5x + 5$
$-x - 5x = 5 - 1$
$-6x = 4$
$x = -\frac{2}{3}$
(11)解:$2(x - 1) - 2 = 4x$
$2x - 2 - 2 = 4x$
$2x - 4x = 4$
$-2x = 4$
$x = -2$
(12)解:$4 - 3(2 - x) = 5x$
$4 - 6 + 3x = 5x$
$-2 = 5x - 3x$
$2x = -2$
$x = -1$
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