第160页 - 江苏版启东中学作业本八年级数学（上下册）

C

-x+y

x-y

2

$x(x^2-y^2)$

x＜2且x≠-1

17

k＞-2且k≠2

-2

2或1

$ \begin{aligned}解：原式&=\frac{3(3x-2)-2(3x-2)+3x^2}{3x(3x-2)} \\ &=\frac{3x^2+3x-2}{3x(3x-2)} \\ \end{aligned}$

$ 解：原式=\frac{m+n}{m+n}+\frac{m^2}{n^2-m^2} $

$~~~~~~~~~~~~~~~~~=1+\frac{m^2}{n^2-m^2} $

$~~~~~~~~~~~~~~~~~=\frac{n^2-m^2+m^2}{n^2-m^2} $

$~~~~~~~~~~~~~~~~~= \frac{n^2}{n^2-m^2} $

$ \begin{aligned} 解：原式&=-x(x-y)·\frac{xy}{x-y} \\ &=-x^2y \\ \end{aligned}$

$ \begin{aligned}解：原式&=\frac{5(x+y)}{3a^2b}·\frac{6a^3b^2}{(x+y)(x-y)} \\ &=\frac{10ab}{x-y} \\ \end{aligned}$