If `f(x)=4x-x^2` then find f(a+1)-f(a-1)

Explanation

To solve the problem, we need to calculate \( f(a+1) - f(a-1) \) given the function \( f(x) = 4x - x^2 \).

### Step 1: Calculate \( f(a+1) \)

We start by substituting \( a+1 \) into the function:

\[
f(a+1) = 4(a+1) - (a+1)^2
...