Let . Find .

To find  A(2), replace t with 2 to get:  3 - 2(2)² +4^2  =  11

To find  A(1), replace t with 1 to get:  3 - 2(1)² +4^1  =  5

To find  A(2) - A(1), subtract the two values. 

so 6? is the answer?

Yes, it is.