If the function g is defined by g (x) = {x/2+5 x_ 7 what is the average rate of change of g over the interval 4<_ x <_ 8

Average rate of change = [ (g (7) - g (4)) / (7 - 4) + (g (8) - g (7)) / (8 - 7) ] = [ (7/2 + 5) - (4/2 + 5) ] / (7 - 5) + [ (-3 (8) + 3) - (-3 (7) + 3) ] / (8 - 7) = [ (8.5 - 7) / 2 + (-21 - (-18)) / 1] = (1.5/2 + (-3)) = 0.73 - 3 = - 2.25