16.函数y=x-x^2的值域是?,函数y=x-x^2(-1≤x≤1)的值域是?

y=x-x^2
=-x^2+x-1/4+1/4
=-(x-1/2)^2+1/4
-(x-1/2)^2<=0
所以y<=1/4
所以值域(-∞,1/4]
y=x-x^2
=-(x-1/2)^2+1/4
-1<=x<=1
则x=1/2,y最大=1/4
x=-1,y最小=-2
所以值域[-2,1/4]