Identities of Squares

For any real numbers $a$ and $b$.

1. Difference of squares

   $a^2-b^2\equiv (a+b)(a-b)$

2. Perfect squares
   1. $(a+b)^2\equiv a^2+2ab+b^2$
   2. $(a-b)^2\equiv a^2-2ab+b^2$
3. Completing the square
   1. $a^2 +b^2 \equiv (a+b)^2 -2ab$
   2. $(a-b)^2 \equiv (a+b)^2 -4ab$

Same Topic:

1. Definitions Identities of Cubes Inverse Variation Measurement of Sound