PreCalculus
posted by Peter on .
How do I find the minimum or maximum of this y = 2x³ + 3x²  12x? It makes 2 curves.

y = 2x^3 + 3x^2  12x
y' = 6x^2 + 6x  12 = 6(x+2)(x1)
y'=0 when x=2 or 1
Knowing what you do about cubic curves, you can see that
the local max occurs at x = 2, and
the local min is at x = 1
y(2) = 20
y(1) = 7