Question 82209
I will only help you with problems 1 and 3 so you can solve all four yourself.

1. (5 + 2a + 3a^2) - (a^2 + a - 6)

= 5 + 2a + 3a^2 - a^2 - a + 6 <-- Group similar terms and perform algebra.

3. (b + 2)(b + 6)

= b^2 + 6b + 2b + 12 <-- Group similar terms and perform algebra.

Please write back if more help is needed.