Answer:
14s^4-7s^2+15
Step-by-step explanation:
At the beginning the only bracket that is changing is the 3rd one because of the minus. (12s^4-6s^2+4s)+(6s^4-4s+27)-4s^4+s^2+12 then open the rest of the brackets. And start calculating.i will just to show you which ones u calculate together. (I'll separate the numbers depending on what they're squared to).
12s^4+6s^4-4s^4=14s^4
-6s^2-s^2=7s^2
27-12=15
All together is 14s^4-7s^2+15