#3**+5 **

I actually used WolframAlpha....we could try some synthetic division - plugging in all the possible factors of 21 over all the possible factors of 4 ... this could be a little time consuming. However, I see that 1 is not a root, so I might test -1...so we have....

-1 4 -15 2 21

-4 19 -21

4 -19 21 0

So....-1 is a root....and we have the 2nd degree polynomial ......4x^2 -19x +21

Factoring this, we have (4x -7) (x-3)

So, the factorization is (x+1)(4x-7)(x-3)

Sorry for not being more thorough the first time, but I was in a hurry !!!

CPhill
Jun 13, 2014

#3**+5 **

Best Answer

I actually used WolframAlpha....we could try some synthetic division - plugging in all the possible factors of 21 over all the possible factors of 4 ... this could be a little time consuming. However, I see that 1 is not a root, so I might test -1...so we have....

-1 4 -15 2 21

-4 19 -21

4 -19 21 0

So....-1 is a root....and we have the 2nd degree polynomial ......4x^2 -19x +21

Factoring this, we have (4x -7) (x-3)

So, the factorization is (x+1)(4x-7)(x-3)

Sorry for not being more thorough the first time, but I was in a hurry !!!

CPhill
Jun 13, 2014