factor
HOW DO YOU FACTOR TRINOMIALS?? any formulas?????
4x² - 5x - 21

Question

factor
HOW DO YOU FACTOR TRINOMIALS?? any formulas?????
4x² - 5x - 21

anonymous · Answer

omg so many peolpe here XD...

zepp · Answer

We have constants 4, -5 and -21

What you are looking for is what numbers (2) summed, get -5, and multiplifed, -21*4.

anonymous · Answer

hm.. only mulitples of 21 are 7 and 3, but how would they add up to -5?

anonymous · Answer

here is solution...

anonymous · Answer

uhm, how did you exactly get the steps? like what did you do to get to the next step? I don't know how you got the next numbers...

zepp · Answer

-21*4 = -84 right?

zepp · Answer

So what numbers multiplied gives -84?
I found 6*-14, 7*-12 and some others.

zepp · Answer

Then 7+-12 = 7-12 = -5, so our two numbers is 7 and -12
Now you can rewrite your trinomials into this form:
$4x^2 +7x -12x -21$

zepp · Answer

and by factoring out some stuffs out
$4x^2-12x+7x-21$
$4x(x-3)+7(x-3)$
$(4x+7)(x-3)$

anonymous · Answer

check my attachment you get answer...

anonymous · Answer

ohhh I see now. kk thanks guys

anonymous · Answer

welcome