Question

{(x+y)(x-2y)-(x+2y)的平方}除2y 求解答过程 速度啊

Answer 1

【开头第一个括号应为(x+2y)】

x=-1 y=1/4

{(x+2y)(x-2y)-(x+2y)^2} ÷ (2y)

= {(x+2y) [(x-2y)-(x+2y)] } / (2y)

= {(x+2y) (-4y) } / (2y)

= -2 (x+2y)

= -2 (-1+2*1/4))

= 1