the rate of change for the points (x1,y1) and (x2,y2) is (y2-y1)/(x2-x1)
given
y=5x^2 and find the slope between x=-2 and x=6
y=6(-2)^2=6(4)=24
y=6(6)^2=6(36)=216
(-2,24)
(6,216)
slope=(216-24)/(6-(-2))=(192)/(6+2)=192/8=96/8=48/4=24/2=12
the rate of change is 12