Do 10/3, which is an estimate. You get an answer of 3.3. Intuitively this makes sense because the slope is a constant positive value. And 1/3 is way too small of a number to describe the steepness shown
Or actually, do 3/1 because that would give the slope from x=0 to x=1. Since the slope is constant, that answer will apply for every single point on the function
