Let P(x) = x2 + ax + b be a quadratic polynomial where a and b are real numbers. Suppose [P(–1)2, P(0)2, P(1)2] is an arithmetic progression of integers. Prove that a and b are integers.
So if b is any rational number then it can be integer only as its square is integer.
should be rational which is not possible for any integer value of m
=> b can not be irrational.
