# How do you factor #y=4x^3+12x^2-16x-48 #?

##### 1 Answer

Jan 24, 2016

you need to find numbers such as :

Because for every monic polynomial of degree

Sum of all root =

Product of all root =

For this take all the divisor of

Sum must be negative so one root is negative, BUT, product is positive so, at least two roots are negative

you find

Of course this method work if coefficient are integers

So :

(x+3)(x+2)(x-2)