Question

Y=1-X2/1+X2的值域怎么求?

Answer 1

1-X2/1+X2→2-(X2+1)/1+X2→-1 + 2/(1+X2)

∵X2≥0 X2+1≥1

0≤2/1+X2≤2

∴-1≤-1+ 2/1+X2≤1

即Y∈〔-1,1〕