- #1

- 7

- 0

Here's one of the questions:

2x

^{3}+3x

^{2}-8x+3

I need a quick 101. Any help would be much appreciated!

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- Thread starter Propagandhi
- Start date

- #1

- 7

- 0

Here's one of the questions:

2x

I need a quick 101. Any help would be much appreciated!

- #2

gb7nash

Homework Helper

- 805

- 1

Here's one of the questions:

2x^{3}+3x^{2}-8x+3

I need a quick 101. Any help would be much appreciated!

Let's call your cubic polynomial f(x). You could use the rational roots test to help you find roots of the polynomial. Once you have a root (call it r), use long division: f(x)/(x-r). This should give you a quadratic, and to find the other two roots(call them s and t) just use the quadratic formula. So in the end, you'll get f(x) = 2(x-r)(x-s)(x-t).

If the rational root test fails, use http://planetmath.org/encyclopedia/CubicFormula.html [Broken] to find your roots. Note that you must factor out a 2 out of the whole expression before you can use these formulas.

Last edited by a moderator:

- #3

- 754

- 1

Try this site:

http://www.1728.com/cubic2.htm

http://www.1728.com/cubic2.htm

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