Mathematics
18 Online
OpenStudy (anonymous):
48x^2+34x-40 factor the trinomial? ( 24+ )( 2- )
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (mathstudent55):
First, factor a common factor from all three terms.
OpenStudy (anonymous):
2?
OpenStudy (mathstudent55):
Yes
OpenStudy (anonymous):
and then?
OpenStudy (anonymous):
(24x+ )(2x- )?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (mathstudent55):
Then you get
2(24x^2 + 17x - 20)
OpenStudy (mathstudent55):
Now that I wrote the method, let's go over it step by step with your problem.
OpenStudy (anonymous):
ok
OpenStudy (mathstudent55):
Your trinomial is 24x^2 + 34x - 20.
When compared to ax^2 + bx + c, you see that you have
a = 24, b = 17, and c = -20.
You follow so far?
OpenStudy (anonymous):
yeah
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (mathstudent55):
Ok, Now let's multiply ac, so we get
24*(-20) = -480
OpenStudy (mathstudent55):
Now we need two factors of -480 that add up to 17
OpenStudy (mathstudent55):
How about -32 and 15?
OpenStudy (anonymous):
yess
OpenStudy (mathstudent55):
Sorry, the other way around. -15 and 32 bec they need to add to +17.
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (mathstudent55):
-15*32 = -480
-15 + 32 = 17
OpenStudy (anonymous):
okay
OpenStudy (mathstudent55):
Now we factor by parts. That means factor a common factor out of the first two terms, and factor out a common factor out of the last two terms.
OpenStudy (mathstudent55):
We need -15 and 32. Now we rewrite the middle term using these two factors:
24x^2 + 32x - 15x - 20
OpenStudy (mathstudent55):
What do 24x^2 and 32x have in common?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
4
OpenStudy (anonymous):
4(6x+8)
OpenStudy (mathstudent55):
4 is the number part. What about x?
OpenStudy (mathstudent55):
You're almost there.
4x(6x + 8)
OpenStudy (anonymous):
okay
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (mathstudent55):
One sec. There is a larger number that can be factored.
OpenStudy (anonymous):
8
OpenStudy (mathstudent55):
24x^2 + 32x = 8x(3x + 4)
OpenStudy (mathstudent55):
Good.
Now what can be factored out of the last two terms?
-15x - 20?
OpenStudy (anonymous):
-5x(3x+4)
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (mathstudent55):
Great. Now let's write everything we have so far, includiong the 2 we originally factored out.
OpenStudy (mathstudent55):
BTW, no x this time
-15x - 20 = -5(3x + 4)
OpenStudy (mathstudent55):
48x^2 + 34x - 40 =
2(24x^2 + 17x - 20) =
2(24x^2 + 32x - 15x - 20) =
2 [ 8x(3x + 4) - 5(3x + 4) ]
The last step now is to pull out the common factor of (3x + 4) inside the brackets:
2 [(3x + 4)(8x - 5) ]
= 2(3x + 4)(8x - 5) (Final answer)
OpenStudy (anonymous):
thank you!!
OpenStudy (mathstudent55):
wlcm