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苏科版宿迁专版 第27页解析答案
解方程:
(1)$5(3-2x)-12(5-2x)= 11$; (2)$(2x-1)+3(4x-7)-5(3x+2)+5= 0$;
(3)$2-\frac {x-5}{6}= x-\frac {x+1}{3}$; (4)$\frac {1-x}{3}-x= 3-\frac {x+2}{4}$;
(5)$\frac {0.1x+0.1}{0.3}-\frac {0.3x-0.5}{0.4}= 1$; (6)$\frac {x-3}{0.15}-\frac {x+4}{0.2}= -10$;
(7)$\frac {3}{2}[2(x-\frac {1}{2})+\frac {2}{3}]= 5x$.
答案:(1)$x=4$ (2)$x=-27$ (3)$x=\frac{19}{5}$ (4)$x=-2$ (5)$x=\frac{7}{5}$ (6)$x=18$ (7)$x=-\frac{1}{4}$
解析:
(1)解:$15 - 10x - 60 + 24x = 11$
$14x - 45 = 11$
$14x = 56$
$x = 4$
(2)解:$2x - 1 + 12x - 21 - 15x - 10 + 5 = 0$
$-x - 27 = 0$
$-x = 27$
$x = -27$
(3)解:$12 - (x - 5) = 6x - 2(x + 1)$
$12 - x + 5 = 6x - 2x - 2$
$17 - x = 4x - 2$
$-5x = -19$
$x = \frac{19}{5}$
(4)解:$4(1 - x) - 12x = 36 - 3(x + 2)$
$4 - 4x - 12x = 36 - 3x - 6$
$4 - 16x = 30 - 3x$
$-13x = 26$
$x = -2$
(5)解:$\frac{x + 1}{3} - \frac{3x - 5}{4} = 1$
$4(x + 1) - 3(3x - 5) = 12$
$4x + 4 - 9x + 15 = 12$
$-5x + 19 = 12$
$-5x = -7$
$x = \frac{7}{5}$
(6)解:$\frac{100x - 300}{15} - \frac{10x + 40}{2} = -10$
$\frac{20x - 60}{3} - (5x + 20) = -10$
$20x - 60 - 15x - 60 = -30$
$5x - 120 = -30$
$5x = 90$
$x = 18$
(7)解:$\frac{3}{2}(2x - 1 + \frac{2}{3}) = 5x$
$\frac{3}{2}(2x - \frac{1}{3}) = 5x$
$3x - \frac{1}{2} = 5x$
$-2x = \frac{1}{2}$
$x = -\frac{1}{4}$
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