Question 68786
<pre>
{{{18a^3 - 24a^2b + 15ab^2 - 20b^3}}}
 
  = {{{(18a^3 - 24a^2b) + (15ab^2 - 20b^3)}}}

Find the common factor :
  = {{{(18a^3 - 24a^2b) + (15ab^2 - 20b^3)}}}

  = {{{6a^2(3a - 4b) + 5b^2(3a - 4b)}}}

Notice that 3a - 4b is a common factor to both terms.
The distributive property can be used to factor out 3a - 4b

  = {{{highlight ((6a^2 + 5b^2)(3a - 4b))}}} </pre>