SOLUTION: the height in feet reached by a batted baeball after t seconds is given by h(t)=-16t^(2)+66t+2, determine when the baseball is 70ft in the air

Click here to see ALL problems on Polynomials-and-rational-expressions

Question 599481: the height in feet reached by a batted baeball after t seconds is given by h(t)=-16t^(2)+66t+2, determine when the baseball is 70ft in the air
Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website!
the height in feet reached by a batted baeball after t seconds is given by h(t)=-16t^(2)+66t+2, determine when the baseball is 70ft in the air
.
Set h(t) to 70 and solve for t:
h(t)=-16t^(2)+66t+2
70=-16t^(2)+66t+2
0=-16t^(2)+66t-68
Using the "quadratic formula" we get:
x = {2, 2.125}
That is, the baseball reaches the height of 70 ft two times:
2 seconds and again at 2.125 seconds
.
Details of quadratic follows:

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=4 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 2, 2.125. Here's your graph: