Answer
$ 2a+h+3$
Work Step by Step
Step 1. Given $f(x)=x^2+3x-1$, we have $f(a)=a^2+3a-1$
Step 2. We have $f(a+h)=(a+h)^2+3(a+h)-1=a^2+2ah+h^2+3a+3h-1$
Step 3. We have $f(a+h)-f(a)=2ah+h^2+3h$
Step 4. Thus, we have $\frac{f(a+h)-f(a)}{h}=2a+h+3$
