I'm stuck on this one....

6r^2-r-2=0

Any assistance appreciated.

Thanks

Thomas

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- Apr 15th 2009, 06:33 AMtbradncFactoring a quadratic equation
I'm stuck on this one....

6r^2-r-2=0

Any assistance appreciated.

Thanks

Thomas - Apr 15th 2009, 06:42 AMmasters
Hi tbradnc,

Here's a technique you can use.

Multiply the leading coefficient (6) by the constant (-2).

This gives you -12.

The coefficient of the middle term is -1.

You need a pair of numbers whose product is -12 and whose sum is -1.

After thinking a bit on this, you should come up with the only combination that works, namely -4 and 3.

Now restate your quadratic replacing the middle coefficient with these two.

$\displaystyle 6r^2{\color{red}-4r +3r}-2$

Now group the first two terms, and then the last two terms.

$\displaystyle (6r^2-4r)+(3r-2)$

Factor each group.

$\displaystyle 2r(3r-2)+1(3r-2)$

$\displaystyle (3r-2)$ is a common factor, so

$\displaystyle (3r-2)(2r+1)$

All done. - Apr 15th 2009, 06:52 AMtbradnc
Thank you so much....I'm so glad I found this site. ;-)

I'm an older adult going back to school and it's been 30 years since I've played with algebra. I leave every class barely understanding what we're doing and I have to drill, drill, drill to get the hang of it.