# Factoring and the Quadratic Formula

• May 5th 2008, 09:15 AM
Nightfire
Yeah...kinda forgot i had this over the weekend, and forgot how to do it. Oops. Anyway...
We're supposed to factor if possible, and then solve with the quadratic formula. I think i got the factoring done, but i can't figure the rest out for the life of me.

\$\displaystyle -2x+6x+9\$

\$\displaystyle -4x^2+8x-2\$
Factor by two...
-2x^2+4x-1
\$\displaystyle -5x^2+5x+5\$
Factor by five...
-x^2+x-1
\$\displaystyle 2x^2+6x-9\$

\$\displaystyle x^2+6x-3\$

did i do the factoring right? and what do i have to do after?
• May 5th 2008, 09:55 AM
r_maths
• May 5th 2008, 10:28 AM
Nightfire
Ok.. i see now. I just couldn't tell what was a/b/c. Thanks!

Now.. how do you determine the plus-or-minus thing?

And does anyone know a way to memorize the quadratic formula aside from Pop Goes the Weasel? :P
• May 5th 2008, 10:33 AM
r_maths
Quote:

Originally Posted by Nightfire
Now.. how do you determine the plus-or-minus thing?

You do 2 seperate equations, one with the plus, the other with the minus.
This should give 2 different values for x.