SOLUTION: Solve using the five-step problem-solving process. Show all steps necessary to arrive at your solution. A water rocket is launched upward with an initial velocity of 48 ft/sec. I

Question 302185: Solve using the five-step problem-solving process. Show all steps necessary to arrive at your solution.
A water rocket is launched upward with an initial velocity of 48 ft/sec. Its height h, in feet, after t seconds is given by h = 48t - 16t2. After how many seconds will the height of the rocket be 20 feet? Show work
can some one please helpme with this
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
h = 48t - 16t2
Set h = 20 and solve for t
20 = 48t - 16t2
-16t^2 + 48t - 20 = 0

Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)

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=1024 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 0.5, 2.5. Here's your graph:

t = x-axis, h = y-axis
It's a 20 ft going up, then again coming down.

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