Question 387724
Think about the height (h) of the stone when it reaches the ground!
It's zero! So you want to find the value of t (time) when the height (h) = 0.
{{{h(t) = -9.8t^2-10t+350}}} Set h(t) = 0 and solve for t.
{{{-9.8t^2-10t+350 = 0}}} Solve using the quadratic formula: {{{t = (-b+-sqrt(b^2-4ac))/2}}} and, here, a = -9.8, b = -10, and c = 350
When you do this you will get:
{{{t = -6.50808}}} or {{{t = 5.4876}}} Discard the negative solution as the time, t, should be a positive quantity.
The stone will hit the ground after 5.49 seconds.