Question

fx=（2x^2+2）/（x^2-1）的值域?

Answer 1

解题思路：用y表示x

解题如下：

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

y(x^2-1)=2x^2+2

yx^2-y=2x^2+2

yx^2-2x^2=2+y

x^2(y-2)=2+y

x^2=(2+y)/(y-2)

x=√(2+y)/(y-2)

所以(2+y)/(y-2)>=0

且y-2不等于0

解得y>=-2且y不等于2