I am asked to factor the equation

$\displaystyle 4x^2 - 4x - 15 = 0$

To my knowledge, your supposed to find pairs of factors that multiply to give -15 and add to give -4, correct?

I can't find a pair that gives both those answers.

I'm stuck.

Printable View

- Apr 23rd 2010, 02:31 PMcantstop01Factoring Question
I am asked to factor the equation

$\displaystyle 4x^2 - 4x - 15 = 0$

To my knowledge, your supposed to find pairs of factors that multiply to give -15 and add to give -4, correct?

I can't find a pair that gives both those answers.

I'm stuck. - Apr 23rd 2010, 02:38 PMskeeter
- Apr 23rd 2010, 02:55 PMcantstop01
Thanks, looks like the answer is $\displaystyle x = 5/2$ and $\displaystyle x = -3/2$

I would like to ask one more thing.

what is the reasoning behind the factors not actually adding up to -4, yet still being the correct answer? - Apr 23rd 2010, 03:12 PMskeeter