Factoring equations

Question

Factor 18x²+9x-20 completely.

Answer 1

Try factoring 18*20.

18*20=2*3*3*2*2*5

rearrange the factors

(2*2*2*3)*(3*5)=24*15 and 24-15=9

24=6*4 and 15=3*5

Answer 2

The first term is 18x² and last term is -20.  Write a product of two binomials in which the product of first terms of both binomials is 18x² and last terms is -20, but making sure that the sum of the product of inner and outer terms is 9x.  This may take trial and error, unless you hit that pot of gold.

 

 

(6x - 5)(3x + 4)