Find the condition that the equation (m ^ 2-m-2) x ^ 2 + MX + M = 0 about X is a quadratic equation with one variable

Find the condition that the equation (m ^ 2-m-2) x ^ 2 + MX + M = 0 about X is a quadratic equation with one variable

If it is a quadratic equation of one variable, then the coefficient of quadratic term is not equal to 0
That is: m ^ 2-m-2 ≠ 0
(m-2)(m+1)≠0
Then: m ≠ 2, m ≠ - 1