第66页 - 启东中学作业本七年级数学苏科版宿迁专版

B

(2-x)²

-3

27

$ \begin{aligned}解：原式&=2(a²-4) \\ &=2(a-2)(a+2). \\ \end{aligned}$

$ \begin{aligned} 解：原式&=-(x²+2xy+y²) \\ &=-(x+y)². \\ \end{aligned}$

$ \begin{aligned}解：原式&=(4x²+1)(4x²-1) \\ &=(4x²+1)(2x-1)(2x+1). \\ \end{aligned}$

$ \begin{aligned}解：原式&=mn(m²-1) \\ &=mn(m+1)(m-1). \\ \end{aligned}$

$ \begin{aligned}解：原式&=a(b²-2b+1) \\ &=a(b-1)². \\ \end{aligned}$

$ \begin{aligned}解：原式&=(a²-b²)(x-y) \\ &=(a-b)(a+b)(x-y). \\ \end{aligned}$

A

(a²+1)(a+2)(a-2)