Question

计算:a+2/a^2-2a×a^2-4a+4/a+2 , x-2/x^2-1÷x+1/x^2+2x+1 , (2x/x-2-x/x+2)÷x/x^2-4

1/a-1 -1-a , (a/a^2-b^2-1/a+b)÷b/b-a(要过程）

Answer 1

a+2/a^2-2a×a^2-4a+4/a+2 ,
=(a+2)/a(a-2)×(a-2)²/(a+2)
=(a-2)/a

x-2/x^2-1÷x+1/x^2+2x+1 ,
=(x-2)/(x-1)(x+1)÷(x+1)/(x+1)²
=(x-2)/(x-1)

(2x/x-2-x/x+2)÷x/x^2-4
=[(2x²+4x-x²+2x)/(x-2)(x+2)]*(x-2)(x+2)/x
=(x²+6x)/x
=x+6

1/a-1 -1-a ,
=1/(a-1)-(a+1)
=(1-a²-1)/(a-1)
=-a²/(a-1)

(a/a^2-b^2-1/a+b)÷b/b-a
=[(a-a+b)/(a-b)(a+b)]÷(-b)/(a-b)
=-1/(a+b)