Please help Soon!!

Question

2x^2+13x-7=

 

Or is it prime?

Answer 1

Hi again David;

2x²+13x-7

For the FOIL...

FIRST must be (2x)(x)=2x²

OUTER and INNER must add-up to 13x

LAST must be (7)(1) or (1)(7) and one number must be negative.

(2x-1)(x+7)

Let's FOIL...

FIRST...(2x)(x)=2x²

OUTER...(2x)(7)=14x

INNER...(-1)(x)=-1x=-x

LAST...(-1)(7)=-7

2x²+14x-x-7

2x²+13x-7

Answer 2

 Another way of looking at it.

 

  2 X² +13X -7

 

  If this is factorable then    

 

there should be 2 integers whose difference is  +13, and product - 14, they are +14, -1

 

2X² + 14X - X - 7 =2X ( X +7) - ( X + 7 ) = ( 2X - 1 ) ( X + 7)

* ( factoring by group )