What are the first, fourth and eighth terms for a(n)=-2*2^n-1

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)

Ihonestly have no clue if it's each or none.

1. 2. ∠b and ∠y are right angles. 3.? 4.? which two statements are missing in steps 3 and 4? ∠x ≅ ∠c △abc ~ △zyx by the sas similarity theorem. ∠b ≅ ∠y △abc ~ △zyx by the sas similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem. = 2 △abc ~ △zyx by the sss similarity theorem.