The decreasing interval of the function y = log0.8 (- X & # 178; + 4x) is

The decreasing interval of the function y = log0.8 (- X & # 178; + 4x) is

Y = log0.8 (- x ^ 2 + 4x) decreases in the whole domain
Its definition field is - x ^ 2 + 4x > 0, that is, x ^ 2-4x = x (x-4)