Local minimum and local maximum problem

The function f(x) = 2x^3 − 36x^2 + 192x + 9 has one local minimum and one local maximum.
This function has a local minimum at x equals=.......... with value............
and a local maximum at x equals=.............. with value.............

local max/min where y'=0
or tangent is a horizontal line

f'(x)= 6x²-72x +192 =0

x=4 and x=8
f(4)=
f(8)=
by graphing it
max where x=4 min where x=8

or you can take second derivative, find out where it concaves up or down.