Which of the following is a factor of the polynomial 6x^2-x-15

Question

A) (6x+3)

 

 

B) (2x+5)

 

 

C) (x+15)

 

 

D) (3x-5)

Answer 1

6x² - x - 15

 

1.  Look for factors each term has in common.

    There are none in this expression,

 

2.  Multiply the coefficient of the square term, 6, by the

     constant, -15.    6(-15) = -90

 

3.  Look for factors of the product that add to the coefficient

     of the middle term, -1

     -10(9) = -90  and  -10+9 = -1

 

4.  Replace -x with -10x + 9x

     6x²-x-15 = 6x² + 9x - 10x -15

 

5.  Factor by grouping

    (6x² + 9x) + (-10x - 15)

    3x(2x+3) -5(2x+3)

    (3x-5)(2x+3)