1. 解下列方程:
(1)$5x+3=3x-15$;
(2)$0.6x=\dfrac{1}{5}x-3.$
(1)$5x+3=3x-15$;
(2)$0.6x=\dfrac{1}{5}x-3.$
答案
(1)移项,得$5x-3x=-15-3$,合并同类项,得$2x=-18$,系数化为1,得$x=-9$.
(2)移项,得$0.6x-\dfrac{1}{5}x=-3$,合并同类项,得$0.4x=-3$,系数化为1,得$x=-7.5$.
(2)移项,得$0.6x-\dfrac{1}{5}x=-3$,合并同类项,得$0.4x=-3$,系数化为1,得$x=-7.5$.
2. 解下列方程:
(1)$3(2 - x) = 4 - x$;
(2)$2(x - 1) - 3(x + 1) = - 6$;
(3)$2(3 - x) = - 4(x + 5)$;
(4)$2(y + 2) - 3(4y - 1) = 9(1 - y)$;
(5)$5(2x - 1) = 2(1 + 2x) + x - 2$;
(6)$x - \dfrac{1}{3}[x - \dfrac{1}{3}(x - 9)] = \dfrac{1}{9}(x - 9)$.
(1)$3(2 - x) = 4 - x$;
(2)$2(x - 1) - 3(x + 1) = - 6$;
(3)$2(3 - x) = - 4(x + 5)$;
(4)$2(y + 2) - 3(4y - 1) = 9(1 - y)$;
(5)$5(2x - 1) = 2(1 + 2x) + x - 2$;
(6)$x - \dfrac{1}{3}[x - \dfrac{1}{3}(x - 9)] = \dfrac{1}{9}(x - 9)$.
答案
(1)去括号,得$6-3x=4-x$,移项,得$x-3x=4-6$,合并同类项,得$-2x=-2$,系数化为1,得$x=1$.
(2)去括号,得$2x-2-3x-3=-6$,移项,得$2x-3x=-6+2+3$,合并同类项,得$-x=-1$,系数化为1,得$x=1$.
(3)去括号,得$6-2x=-4x-20$,移项、合并同类项,得$2x=-26$,系数化为1,得$x=-13$.
(4)去括号,得$2y+4-12y+3=9-9y$,移项、合并同类项,得$-y=2$,系数化为1,得$y=-2$.
(5)去括号,得$10x-5=2+4x+x-2$,移项,得$10x-4x-x=2-2+5$,合并同类项,得$5x=5$,系数化为1,得$x=1$.
(6)去括号,得$x-\dfrac{1}{3}x+\dfrac{1}{9}x-1=\dfrac{1}{9}x-1$,移项,得$x-\dfrac{1}{3}x+\dfrac{1}{9}x-\dfrac{1}{9}x=-1+1$,合并同类项,得$\dfrac{2}{3}x=0$,系数化为1,得$x=0$.
(2)去括号,得$2x-2-3x-3=-6$,移项,得$2x-3x=-6+2+3$,合并同类项,得$-x=-1$,系数化为1,得$x=1$.
(3)去括号,得$6-2x=-4x-20$,移项、合并同类项,得$2x=-26$,系数化为1,得$x=-13$.
(4)去括号,得$2y+4-12y+3=9-9y$,移项、合并同类项,得$-y=2$,系数化为1,得$y=-2$.
(5)去括号,得$10x-5=2+4x+x-2$,移项,得$10x-4x-x=2-2+5$,合并同类项,得$5x=5$,系数化为1,得$x=1$.
(6)去括号,得$x-\dfrac{1}{3}x+\dfrac{1}{9}x-1=\dfrac{1}{9}x-1$,移项,得$x-\dfrac{1}{3}x+\dfrac{1}{9}x-\dfrac{1}{9}x=-1+1$,合并同类项,得$\dfrac{2}{3}x=0$,系数化为1,得$x=0$.
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