Question 84165: Factor 3a2-13a+ 12
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! First of all, let me suggest that you check out my Lesson Plans on Factoring in algebra.com, especially the lessons pertaining to "Advanced Trinomial Factoring." See also my own website by clicking on my tutor name "rapaljer" anywhere in algebra.com, then look for "MATH IN LIVING COLOR", then "Basic Algebra", the look for Chapter 2, the topic "Advanced Trinomial Factoring."
Now,  has to start off with the First times First to be 3a times a
The Last times Last has to be two numbers whose product is 12. This could be
1*12
2*6
3*4
However, because the middle term is an ODD number, you cannot use an EVEN-EVEN combination of numbers. Start with 3*4.
Because the last term is POSITIVE, you must find an OUTER times OUTER and INNER times INNER combination that will ADD together to give you -13 for the middle term. By trial and error, the combination that works is this:
Notice that the OUTER times OUTER is -9x and the INNER times INNER is -4x, and this adds up to the middle term which is -13x.
See my Lesson Plans and website for additional explanations.
R^2 at SCC
|
|
|
