SOLUTION: I am having trouble setting up the quadratic equation from this word problem. A missile fired straight up into the air has a height, in meters, given by h=-5t^2+15t, where t is

Question 941528: I am having trouble setting up the quadratic equation from this word problem.
A missile fired straight up into the air has a height, in meters, given by h=-5t^2+15t, where t is the time, in seconds, the missle has been in the air. By setting up and solving an equation, find the time when the missle hits the ground.
after_____seconds

Found 2 solutions by nerdybill, josgarithmetic:
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
A missile fired straight up into the air has a height, in meters, given by h=-5t^2+15t, where t is the time, in seconds, the missle has been in the air. By setting up and solving an equation, find the time when the missle hits the ground.
after_____seconds
.
Since"h" is the height, when the missile hits the ground, h should be zero.
Our equation:
0 = -5t^2+15t
factor the right
0 = (-5t)(t-3)
t = {0, 3}
throw out the 0, this represents when the missile was fired.
Answer: 3 seconds
Answer by josgarithmetic(39616) (Show Source): You can put this solution on YOUR website!
and take the positive t value.
RELATED QUESTIONS
A missile fired straight up into the air has a height, in feet, given by h = -16 t^2 + 64 (answered by solver91311)
A missile fired straight up into the air has a height, in meters, given by h = -5 t^2 +... (answered by mananth)
A missile fired straight up into the air has a height, in meters, given by h = -5 t^2 +... (answered by richwmiller)
A Missile fired straight up in to the air has the height, in feet, given by h=-16t^2+32t, (answered by Alan3354)
Quadratic equation hidden in a word problem. A firecracker is fired straight up into... (answered by MathLover1)
Please help me solve this equation. The height h of a missile after t seconds, when... (answered by MathLover1)
A firecracker is fired straight up into the air out of a window of a building. Its... (answered by lwsshak3)
A firecracker is fired straight up into the air out of a window of a building. Its... (answered by LinnW)
This is a word problem my teacher made up for us. I am having trouble setting it up.... (answered by stanbon)