FACTORIZE K1

 

Factorize 4x² - 7x – 15.

 

Solution

 

= 4x² - 7x – 15. 

 

We split the middle term (-x)

 

We look for two items such that

mxn =  4x² x (-15)= -60x²and

m+n = -7x

The correct choice is -12x and 5x:

 

= 4x² - 12x + 5x – 15            Since    (-7x) = -12x + 5x.

 

= (4x² - 12x) + (5x - 15)    grouping the factors

 

= 4x(x - 3) + 5(x - 3)  factoring out common terms

 

= (4x + 5) (x - 3)  answer

 

Hence 2x² - x – 15 = (2x + 5) (x - 3) answer.

 

TRY THIS…..

 

 Factorize 3x² - 16x – 35.