I'm trying to teach myself calculus and have come across this problem.
I have a function of x
f(x) = x^3 + 5x^2 - 8x - 12
so I set this to zero by
f'(x) = 3x^2 + 10x - 8 = 0
then the book I'm using says that I can find the local values of x for min and max and these should be x1 = 0.667 and x2 = -4.000 but it doesn't say how these figures are reached.
Could someone guide me in the right direction please.
Thanks in advance