Question

函数y=x的平方+1分之x的平方减一的值域是?

Answer 1

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

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

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

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

由 x^2>=0 得 (-y-1)/(y-1)>=0 ,

所以 (y+1)/(y-1)