+0

# Factoring

+1
175
3
+681

Factor this expression.

\(-2x^2+x+21=0\)

AdamTaurus  Sep 13, 2017

#1
+5905
+3

Hey! This is the same equation that you get from the last question.

You can solve it by factoring like this....

-2x2 + x + 21  =  0

Multiply the  -2  and  21  to get  -42  .

Now split the middle term with two numbers that add to  1  and multiply to  -42 .

-2x2 - 6x + 7x + 21  =  0

Factor a  -2x  out of the first two terms and a  7  out of the last two terms.

-2x(x + 3) + 7(x + 3)  =  0

Factor  a  (x + 3)  out of both remaining terms.

(x + 3)(-2x + 7)  =  0

hectictar  Sep 13, 2017
Sort:

#1
+5905
+3

Hey! This is the same equation that you get from the last question.

You can solve it by factoring like this....

-2x2 + x + 21  =  0

Multiply the  -2  and  21  to get  -42  .

Now split the middle term with two numbers that add to  1  and multiply to  -42 .

-2x2 - 6x + 7x + 21  =  0

Factor a  -2x  out of the first two terms and a  7  out of the last two terms.

-2x(x + 3) + 7(x + 3)  =  0

Factor  a  (x + 3)  out of both remaining terms.

(x + 3)(-2x + 7)  =  0

hectictar  Sep 13, 2017
#2
+681
+1

The other guy's answer really confused me because he didn't know how to use Latex, so I worked most of it out as best I could then asked this.

AdamTaurus  Sep 13, 2017
#3
+91436
0

Thanks Hectictar,

Adam, I hope that you said 'thank you' to both of your answerers!

So far I have not seen even one though

Melody  Sep 13, 2017

### 17 Online Users

We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details