solve for time
S=-10t^2+6t+50
You cannot solve for time unless you know that S is.
You can always use the quadratic equation for t in terms of S:
t = (1/20)[-6 +/- sqrt[36+4*10*(S-50)]
S=-10t^2+6t+50
You can always use the quadratic equation for t in terms of S:
t = (1/20)[-6 +/- sqrt[36+4*10*(S-50)]