Tìm Max: A = 4 - x^2 + 2x; B = 4x - x^2; C = x^2 + 6x + 4

2.Tìm Max
a) A= 4-x^2+2x
b) B= 4x-x^2
c) C= x^2+6x+4
3. Cho x+2y=3
Tìm min P= x^2+y^2+2xy