Question

化简并求值：（1x-y+ 1x+y）÷2x-yx2-y2,其中x、y满足∣x-2∣+(2x-y-3)²=0.

Answer 1

解：∵∣x-2∣+(2x-y-3)2=0，

        ∣x-2∣=0  ，      x=2

∴                                                                            (2x-y-3)2=0 ,      y=1  ， 

将原式化简：   

（1x-y+ 1x+y）÷2x-yx2-y2= 2x(x-y)(x+y)(x-y)(x+y)2x-y= 2x2x-y

将  x=2，y=1代入 2x2x-y得：

原式= 2×22×2-1= 34. Www.12999.com