If the definition field of function f (x) = (MX ^ 2 + 4x + m + 2) ^ - 3 / 4 + (x ^ 2-mx + 1) ^ 1 / 2 is r, find the value range of real number M The answer is (√ 5) - 1

If the definition field of function f (x) = (MX ^ 2 + 4x + m + 2) ^ - 3 / 4 + (x ^ 2-mx + 1) ^ 1 / 2 is r, find the value range of real number M The answer is (√ 5) - 1

The function is meaningful and needs to meet the following conditions: MX ^ 2 + 4x + m + 2 > 0, x ^ 2-mx + 1 ≥ 0 (non negative number under root sign, denominator not 0)
From the parabola image, when x ∈ R, the inequality must be m > 0, that is, the opening is upward
It also needs to meet the following requirements: △ 1 = 4 ^ 2-4m (M + 2)