先化简再求值 x/(x+2)-(x²+2x)/(x-5)÷[(x²-1)/(x-1)] 其中x=根号三-2

问题描述:

先化简再求值 x/(x+2)-(x²+2x)/(x-5)÷[(x²-1)/(x-1)] 其中x=根号三-2

原式=x/(x+2)-x(x+2)/(x-5)÷(x+1)
=x/(x+2)-x(x+2)/(x-5)(x+1)
=[x(x-5)(x+1)-x(x+2)(x+2)]/(x+2)(x-5)(x+1)
=(-8x^2-9x)/(x+2)(x-5)(x+1)

=x/(x+2)-x(x+2)/(x-5)÷(x+1)
=x/(x+2)-x(x+2)/(x-5)(x+1)
=[x(x-5)(x+1)-x(x+2)(x+2)]/(x+2)(x-5)(x+1)
=(-8x^2-9x)/(x+2)(x-5)(x+1)