f(x)=Bx^{K}+Ax^I
.
Compute f'(1)
.First, f'(x)=B(Kx^{K-1})+
A(Ix^{I-1})
.
Then f'(x)=B*Kx^{K-1}+A*Ix^{I-1}
.
Then f'(1)=K*B+A*I
.
Now you just have to do the addition.