Thread: factoring (common factoring complex trinomials)

so the exuation is :

2x^2+18x+40


I know I have to common factor first, but I don't know exaclly where to go from there. It's grade 10 accademic math..I duuno if that means anything?

so I put it so it was like this:


2(x^2+9x+20)



and I duuno where to go from there?

Any help would be appreciated.

Originally Posted by smallman_11

so the exuation is :

2x^2+18x+40


I know I have to common factor first, but I don't know exaclly where to go from there. It's grade 10 accademic math..I duuno if that means anything?

so I put it so it was like this:


2(x^2+9x+20)



and I duuno where to go from there?

Any help would be appreciated.

And how does that factor?

Thus the answer is,
.

Thank you

Originally Posted by smallman_11

...
2(x^2+9x+20)

and I duuno where to go from there?
Any help would be appreciated.

Hello, smallman,

I presume that you are a little bit uncertain how to factorize


To do this probelm you must know the binomial formulae:
(a+b)² = a² + 2ab + b² [1]
(a-b)² = a² - 2ab + b² [2]
(a+b)(a-b) = a² - b² [3]

The formula [3] is very important with your problem:
1. Complete square with the first two summands by adding a third summand and subtract this summand immediately:
=
2. Unite the first three summands to a binom [1] and the last two summands to a square:


3. Now you've got a term similar to the RHS of formula [3]. Use the LHS of this formula:



4. Finally you get:



That's the TPH's result.

EB