Given that a, B, C are real numbers, f (x) = AX2 + BX + C, G (x) = ax + B, when - 1 ≤ x ≤ 1 | f (x) | ≤ 1. (1) prove: | C | ≤ 1; (2) prove: when - 1 ≤ x ≤ 1, | g (x) | ≤ 2; (3) let a > 0, when - 1 ≤ x ≤ 1, the maximum value of G (x) is 2, and find f (x)

Given that a, B, C are real numbers, f (x) = AX2 + BX + C, G (x) = ax + B, when - 1 ≤ x ≤ 1 | f (x) | ≤ 1. (1) prove: | C | ≤ 1; (2) prove: when - 1 ≤ x ≤ 1, | g (x) | ≤ 2; (3) let a > 0, when - 1 ≤ x ≤ 1, the maximum value of G (x) is 2, and find f (x)


(1) In this paper, we prove: from the condition that when = 1 ≤ x ≤ 1, we can get the following result: |c