SOLUTION: Not sure if this is in the right area. But the problem says" Factor the following expression." The problems is as follows: (x-2y)^3 - (x+4)^3

Algebra ->  Expressions-with-variables -> SOLUTION: Not sure if this is in the right area. But the problem says" Factor the following expression." The problems is as follows: (x-2y)^3 - (x+4)^3      Log On


   



Question 185775: Not sure if this is in the right area. But the problem says" Factor the following expression."
The problems is as follows:
(x-2y)^3 - (x+4)^3

Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Not sure if this is in the right area. But the problem says" Factor the following expression."
The problems is as follows:


%28x-2y%29%5E3+-+%28x%2B4%29%5E3

You have to learn this set of rules:

A%5E3%2BB%5E3=%28A%2BB%29%28A%5E2-AB%2BB%5E2%29
A%5E3-B%5E3=%28A-B%29%28A%5E2%2BAB%2BB%5E2%29

In the second one, 

A%5E3-B%5E3=%28A-B%29%28A%5E2%2BAB%2BB%5E2%29,

substitute %28x-2y%29 for A, and %28x%2B4%29 for B:



Then remove the inner parentheses on the right:





Factor -2 out of the first parentheses.  Combine like terms in
the second parentheses.

%28x-2y%29%5E3-%28x%2B4%29%5E3=-2%28y%2B2%29%283x%5E2-6xy%2B4y%5E2%2B12x-8y%2B16%29

Edwin