posted by casidhe .
Consider the function f(x)=(x^3)(e^9x),
-2 is less than or equal to x is less than or equal to 4
*The absolute maximum value is _____ and this occurs at x equals 4.
*The absolute minimum value is _____ and this occurs at x equals ______
I got the 4 but I must be doing something wrong with the other numbers because it is not working
let's take the derivative
f'(x) = 3x^2 (e^(9x) ) + x^3 (9) e^(9x)
= 3x^2 e^(9x) [ 1 + 3x]
= 0 for a max/min
x = 0 , x = -1/3
f(0) = 0
f(-1/3) = (-1/27) e^-3 = -1/(27e^3) = appr -.00184
f(-2) = -8 e^-18 = -8/e^18 = appr -.0000000121
so the absolute minimum is -8/e^18 , when x = -2
wrong is x=-4