Question

先化简再求值 x²-2x/x÷(x-4/x) 其中x=3

Answer 1

x²-2x/x÷(x-4/x)

=x(x-2)/x×x/(x+2)(x-2)

=x/(x+2)

当x=3时 原式=3/(3+2)=3/5

(1+1/x-2)÷x²-2x+1/x²-4

=(x-1)/(x-2)×(x+2)(x-2)/(x-1)²

=(x+2)/(x-1)

当x=-5时

原式=-3/(-6)=1/2

[1+2x-4/(x+1)(x-2)]÷x+3/x²-1

=(x+3)/(x+1)×(x+1)(x-1)/(x+3)

=x-1

当x=6时

原式=6-1=5