Given the mapping f a → B, a = b = R, the corresponding rule is: X → y = - x2 + 2x, for the real number k belongs to B, there is no original image in a, find K Come on, see who can write it

Given the mapping f a → B, a = b = R, the corresponding rule is: X → y = - x2 + 2x, for the real number k belongs to B, there is no original image in a, find K Come on, see who can write it

A=B=R
K belongs to B
k=-x^2+2x=-(x-1)^2+11