SOLUTION: h=-4.9t^2+12t+45 the object is at a height of 45m. What amount of time will it take to hit the ground?

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Question 1040284: h=-4.9t^2+12t+45
the object is at a height of 45m. What amount of time will it take to hit the ground?

Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.
h = -4.9t^2+12t+45
the object is at a height of 45m. What amount of time will it take to hit the ground?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It will hit the ground when h = 0.

To find t, solve this quadratic equation

= .

Use the quadratic formula (see the lessons
    - Introduction into Quadratic Equations
    - PROOF of quadratic formula by completing the square
in this site).

For similar problems see the lessons
    - Problem on a projectile moving vertically up and down
    - Problem on an arrow shot vertically upward
    - Problem on a ball thrown vertically up from the top of a tower
    - Problem on a toy rocket launched vertically up from a tall platform



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