A mathematical problem about merging similar items ① Known polynomial ax's cube + ax's Square - 2x's cube + 2x's square + X + 1 is a quadratic polynomial about X, find the value of a's square + 1 / A's square + a! ② Try to explain that the sum of any three consecutive integers must be a multiple of 3

A mathematical problem about merging similar items ① Known polynomial ax's cube + ax's Square - 2x's cube + 2x's square + X + 1 is a quadratic polynomial about X, find the value of a's square + 1 / A's square + a! ② Try to explain that the sum of any three consecutive integers must be a multiple of 3

1. Ax ^ 3 + ax ^ 2-2x ^ 3 + 2x ^ 2 + X + 1 = (A-2) x ^ 3 + (a + 2) x ^ 2 + X + 1 is a quadratic polynomial, then the coefficient of x ^ 3 = 0a-2 = 0A = 2A ^ 2 + 1 / A ^ 2 + a = 2 ^ 2 + 1 / 2 ^ 2 + 2 = 25 / 42, let three continuous integers be k-1, K, K + 1 (k is an integer) k-1 + K + K + 1 = 3k, which can be divided by 3, so any three continuous integers can be divided by 3