Algebra

15x^2 - 6x - 9 = 0
Let's divide through by three to make this a little easier - maybe.
5x^2 - 2x - 3 = 0
Let's see if this will factor
(5x + 3) (x - 1) = 0

Yep...that works okay......Can you finish it from here???

mathgeek12:

the problem is: 15x2(2 is an exponent) - 6x - 9 = 0. WHat negative value of x is a solution to the quadratic equation?

15x ² - 6x - 9 = 0

Divide through by 3 just the same as CPhill did.

5x ² - 2x - 3 = 0

Now, how do you go about finding the factors?

5*-3 = -15
You have to look for two numbers that multiply to -15 and add to -2
Since they multiply to a negative number, one will be neg and the other positive. Since they add to a negative, there 'bigger' one will be negative
Must be -5 and +3
-2x becomes -5x+3x

5x ² - 2x - 3 = 0 becomes
5x ² - 5x+3x - 3 = 0
factorise this in pairs
5x(x-1) +3(x-1) = 0
(5x+3)(x-1) = 0

And yes, hopefully you can finish it from there.

Look here for more help
http://web2.0calc.com/questions/grouping-method-and-factorizing-quadratic-equations