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Week 5 in Precalculus 11

What I learned this week is about quadratic trinomials and how to factor them.

 

A quadratic trinomial looks like this:

ax^2 + bx+ c

Remember that a quadratic trinomial always have a degree of 2.

 

Basically, what you need to do for factoring is find two numbers that will multiply to “c”, and also they must add together to have a sum that’s equal to “b”.

We must not forget signs (- / +) and how they work because they’re also necessary for this unit!

 

E.g.

x^2 + 5x + 6

Find factors of 6:

1 x 6 ; -1 x -6

2 x 3 ; -2 x -3

 

Now, what will add to “5”?

1 + 6 = 7 (NO!)

2 + 3 = 5 (YES!)

 

So now, we’re using 2 and 3 as factors.

x^2 + 5x + 6 =(x + 2) (x + 3)

 

As you’ve noticed, what you did was like doing the FOIL method backwards. For information about FOIL METHOD, check out my blog post about FOIL.