Factoring Trinomials Using
FOIL Reversed
. . .also called guess and check
FACTORING POLYNOMIALS
GCF isfirst!
Are there any squared
terms left over?
2 Terms It is possibly the difference of two squares (DOTS)
3 TermsIf a = 1, do guess and check. If a is a number other than 1, do guess/check or factor by grouping (product/sum).
4 Terms Factor by grouping.
We’ll look into this
one today.
2 8 15y y FACTOR:
FACTORING is likeplaying JEOPARDY. Youhave the answer and must get the question.
2 8 15y y FACTOR:
( )( )
(y )(y )
2 8 15y y FACTOR:
(y )(y )
(y 5)(y 3)
2 8 15y y (y 5)(y 3)
Wait until later to decide what signs go there.
2 8 15y y (y 5)(y 3)
15 could be5 times 3
Or-5 times -3
2 8 15y y
( 5)( 3)y y Try:
3y
5y
2 8 15y y
3y 5yand
don’t make –8y.
2 8 15y y
PLUS
HAS TO ADD UP TO THE MIDDLE TERM.
2 8 15y y
( 5)( 3)y y Try:
3y
5y
2 8 15y y ( 5)( 3)y y
There is a lot more to factoring.It takes lots of practice.