You are correct.
A soccer ball is kicked into the air so that its height, h in metres, after t seconds is modelled by the function h(t)= -4.9t(squared)+12t+0.5
h=0.05
Estimate the instantaneous rate of change of the height of the ball after 2 s.
I got -7.6, but I'm not sure if that's right, any help would be appreciated