Need help factoring this equation using the difference of two squares

**ryanch94** · September 18th 2011, 05:07 AM

not entirely sure how to do it could someone explain it to me?

(2x + y)^2 - 4

- '^2' being the power of 2 if its unclear :P

**piscoau** · September 18th 2011, 05:08 AM

by letting 2x+y = a
then the equation will become
a^2-4
=(a-2)(a+2)
=(2x+y-2)(2x+y+2)

please refer to the identity (a-b)(a+b)=a^2-b^2

**Prove It** · September 18th 2011, 05:08 AM

Originally Posted by ryanch94

not entirely sure how to do it could someone explain it to me?

(2x + y)^2 - 4

- '^2' being the power of 2 if its unclear :P

Does it help if you write it as $\displaystyle (2x + y)^2 - 2^2$ ?

**ryanch94** · September 18th 2011, 05:12 AM

Originally Posted by piscoau

by letting 2x+y = a
then the equation will become
a^2-4
=(a-2)(a+2)
=(2x+y-2)(2x+y+2)

please refer to the identity (a-b)(a+b)=a^2-b^2

Cheers for that! Seems quite simple now! :L

Thread: Need help factoring this equation using the difference of two squares