Just distribute. a^2 x a is a^3. 2a x a is 2a^2. 1 x a is a. So far we have a^3 +2a^2+a. Now do the other side. a^2 x 1 is a^2. 2a x 1 is 2a. And 1 x 1 is 1. Now we combine like terms. 2a^2 + a^2 is 3a^2. 2a + a is 3a. Now we just write the equation. a^3+3a^2+3a+1 is the answer.