Question

要使分式x²-1/x²-x的值为0,x应取何值

Answer 1

分式值为0,分子=0,分母≠0

(x²-1)/(x²-x)=(x+1)(x-1)/[x(x-1)]

分式有意义,分母≠0,x≠0且x≠1

分子=0

(x+1)(x-1)=0

x=-1或x=1(舍去)

x=-1