Hi,

What is the general method for factoring 3rd degree polynomials? Such as:

$\displaystyle 9x^3+7x^2-3x+90=0$

Thanks!

-Masoug

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- Nov 2nd 2010, 05:31 PMmasougHow to Factor 3rd Degree (and Higher) Polynomials
Hi,

What is the general method for factoring 3rd degree polynomials? Such as:

$\displaystyle 9x^3+7x^2-3x+90=0$

Thanks!

-Masoug - Nov 2nd 2010, 05:39 PMWilmer
Use google; you'll get sites like:

How to Factor Cube Functions | eHow.com - Nov 3rd 2010, 06:43 AMHallsofIvy
The only "general method" for factoring polynomials, even quadratic polynomials, is to solve the equation. If $\displaystyle x_1$, $\displaystyle x_2$, ..., $\displaystyle x_n$ are roots of $\displaystyle ax^n+ bx^{n-1}+ \cdot\cdot\cdot+ yx+z= 0$ then $\displaystyle ax^n+ bx^{n-1}+ \cdot\cdot\cdot\+ z= a(x- x_1)(x- x_2)\cdot\cdot\cdot(x- x_n)$.

Other than that, you do exactly the sort of thing you do for quadratics- look at the factors of the leading coefficient and constant term and try to distribute them among the factors.

Of course, MOST polynomials, even quadratic polynomials,**cannot**be factored using only integer coefficients, which is what is usually understood by "factoring".