SOLUTION: Solve step by step. 18. A tennis ball is launched straight upward with an initial velocity of 24.5 m/s from the edge of a cliff that is 117.6 meters above the ground. Which

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Question 1155163: Solve step by step.
18. A tennis ball is launched straight upward with an initial velocity of 24.5 m/s from the edge of a cliff that is 117.6 meters above the ground. Which quadratic equation could be used to correctly determine when the ball will hit the ground:

4.9t^2 + 24.5t + 117.6 = 0
-4.9t^2 - 24.5t + 117.6 = 0
-4.9t^2 + 24.5t - 117.6 = 0
4.9t^2 + 24.5t - 117.6 = 0
-4.9t^2 + 24.5t + 117.6 = 0
19. Solve the equation you chose in question 18 to determine when the ball will hit the ground. (HINT: If you don't get one of the answers listed for this question, then maybe you chose the wrong equation in #18. Use this opportunity to double check your work!)

t = 8 seconds
t = 4 seconds
t = 3 seconds
t = -3 seconds
The ball will never reach the ground.

20. Using the same equation, determine when the ball is at a height of 49 meters.
Answer by ewatrrr(24785) (Show Source):
You can put this solution on YOUR website!

Hi
18. 4.9t2 + 24.5t - 117.6 = 0
19. t = (-24.5 +( 24.5^2 + 4x4.9x117.6)^0.5)/ 9.8
t = 3 seconds.
20. 4.9t2 + 24.5t - 49 = 0
t = (-24.5 +( 24.5^2 + 4x4.9x 49 )^0.5)/ 9.8

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=1560.65 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 1.53112887414928, -6.53112887414928. Here's your graph: