SOLUTION: Can someone help me with this problem i have no idea where to even start. The height "h" in feet of an object after "t" seconds is given by the function h = -16t^2+70t+8 H

Question 78020: Can someone help me with this problem i have no idea where to even start.
The height "h" in feet of an object after "t" seconds is given by the function
h = -16t^2+70t+8
How long will it take the object to hit the ground? Round the answer to the nearest thousandth.
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
To figure out when the object will hit the ground, let h=0 and solve for t. This means we can use the quadratic formula:

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=5412 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: -0.11144676971869, 4.48644676971869. Here's your graph:

Ignoring the negative time, we get

So the object will hit the ground at about 4.49 seconds
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