I HAVE TWO QUESTIONS: I HAVE TO MULTIPLY AND SIMPLIFY AND I HAVE NO CLUE HERE ARE THE PROBLEMS:

1. 7a-21a^2/9a^2+6a+1 x 9a^2+6a+1/9a^2-1

2. 2a+2/8a+24 x 4x+12/2x^2-2

You have to use brackets.

I think you mean ...
(7a-21a^2)/(9a^2+6a+1) (9a^2+6a+1)/(9a^2-1)

= 7a(1 - 3a)/(9a^2+6a+1) (9a^2+6a+1)/((3a-1)(3a+1))
= -7a/(3a+1)

the second one factors nicely too once you put the brackets in