How do you factor the expression #15x^2-2x-8#?

2 Answers
Jan 19, 2016

Answer:

#(5x-4)(3x+2)#
#15x^2-12x+10x-8#

Explanation:

Check for a product what product:
#(-2-3x) (4-5x)#
Multiply and test:
#-8-12x+10x+15x^2#
Multiply by negative one if you like and have the factors in the answer form
Wich recovers the original quadratic equation

Jan 19, 2016

Answer:

#(5x-4)(3x+2)#

Explanation:

First, you have to find the zeros of the expression, with the general expression

#x=(-b+-sqrt(b^2-4ac))/(2a)#

#x=(2+-sqrt(2^2-4*15*8))/(2*15)#

#x=(2+-sqrt(484))/(30)#

#x=(2+-22)/(30)#

#x=24/30# or #x=-20/30#

#x=4/5# or #x=-2/3#

Finding the zeros we can factorize the expression:

#15(x-4/5)(x+2/3)#

We can continue further to

#5(x-4/5)*3(x+2/3)#

#(5x-4)(3x+2)#