The known function f (x) = - 2A & # 178; X & # 178; + ax + 1 If f (x) = - 2A & # 178; X & # 178; + ax + 1 ≤ 0 is constant in the interval (1, + ∞), find the value range of real number a

The known function f (x) = - 2A & # 178; X & # 178; + ax + 1 If f (x) = - 2A & # 178; X & # 178; + ax + 1 ≤ 0 is constant in the interval (1, + ∞), find the value range of real number a

F (x) must satisfy the following conditions:
f(1)