Hello, I'am having problems with factoring 40X^3 - 5 can anyone show me how to do this?

- Martingale
**Posts:**333**Joined:**Mon Mar 30, 2009 1:30 pm**Location:**USA-
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Hello, I'am having problems with factoring 40X^3 - 5 can anyone show me how to do this?

http://en.wikipedia.org/wiki/Factorizat ... _two_cubes

OK, thanks for the relply, I know thanks to the Wikipedia factoring page you send me, how to solve this problem now.

I divide each term by 5 to get 8x^3 - 1 that turns in to (2x)^3 - 1^3, then 2x - 1 is a factor, the other factor is found by long division of (2x^3 - 1)/ (2x - 1) = 4x^2 + 2x + 1. I now have to multiply one of the factors by 5 again to make up for the first division by 5. So 40x^3 - 5 = 5 (2x -1) (4x^2 + 2x + 1).

Thank you very much for your help.

Greetings.

Luke.

I divide each term by 5 to get 8x^3 - 1 that turns in to (2x)^3 - 1^3, then 2x - 1 is a factor, the other factor is found by long division of (2x^3 - 1)/ (2x - 1) = 4x^2 + 2x + 1. I now have to multiply one of the factors by 5 again to make up for the first division by 5. So 40x^3 - 5 = 5 (2x -1) (4x^2 + 2x + 1).

Thank you very much for your help.

Greetings.

Luke.