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## Homework Statement

My problem is that whenever I have to use cubic functions - whether it's finding the roots (when dy/dx kis a cubic function) or finding the x-intercepts... With quadratic functions I usually use the quadratic formula. I try to figure out how to factor these equations in my head but I can rarely get it right.

Right now my problem is with finding the x-intercepts of

y = 2x

^{3}- 3x

^{2}- 12x

## Homework Equations

Finding the local maximum/minimum when dy/dx = 4x

^{3}+ 12x

^{2}- 4x - 12

## The Attempt at a Solution

I've tried using newton's method on the relevant equation question, but that failed. x

_{1}equalled -3 and x

_{2}equalled 109, using an initial guess of 1. I won't put working because I think this really isn't what I'm supposed to do.

Don't really need answers to these questions, just really need some help on how to deal with cubic functions. Thanks a lot if anyone can help.