If the function y = x ^ 2-6x + 4 is a decreasing function in the interval [0, M], then the value range of M is

If the function y = x ^ 2-6x + 4 is a decreasing function in the interval [0, M], then the value range of M is

Because the decreasing interval of the function y = x ^ 2-6x + 4 is
(negative infinity, 3), [0, M] is contained in the decreasing interval, so 0