A calculator was dropped at an equation of d= 0.5*9.8t^2 + 5t
How long would it take for the calculator to hit the ground? HINT: SET THE EQUATION TO ZERO.
so, follow the hint
4.9t^2 + 5t = 0
t(4.9t+5)=0
a product is zero if either factor is zero.
Now, do you see a problem with your equation for d?
Hint: if t>0, d will never be 0.