a. f'(x)=2x-1. On the graph the slope between 1 and 2 is almost a straight line: f(2)=-1, f(1)=-3. The slope is therefore (f(2)-f(1))/(2-1)=2. The slope between 0 and 1 is 0 (flat) on average so the average of 2 and 0 is (2+0)/2=1. The average slope can also be seen by drawing a line from (2,-1) to (0,-3). The slope is (-1-(-3))/(2-0)=2/2=1.
b. -1. The slope is negative (\) and is 45 degrees.
c. 3. The slope is positive (/) and fairly steep (about 71 degrees).