Math
posted by jonh .
f(x)=√(x)(x4)
find the critical number

Assuming you meant
f(x) = √((x)(x4))
f'(x) = (x2)/√((x)(x4))
So, x=2 is the critical value
except that f(x) is not defined for 0<x<4
If you meant f(x) as written,
f'(x) = (3x4)/(2√x)
and the critical value is x = 4/3