Question

(09.06 HC)

The function H(t) = -16t2 + 90t + 75 shows the height H(t), in feet, of a projectile after t seconds. A
second object moves in the air along a path represented by g(t) = 31 + 32.2t, where g(t) is the height, in
feet, of the object from the ground at time t seconds.
Part A: Create a table using integers 2 through 5 for the 2 functions. Between what 2 seconds is the
solution to H(t) = g(t) located? How do you know? (6 points)
Part B: Explain what the solution from Part A means in the context of the problem.(4 points)

Answer 1

Answer: h(t) = g(t) between 4 and 5 seconds

Explanation:

h(t) = -16t² + 90t + 75

g(t) = 31 + 32.2t

`\begin{array}c\qquad&\underline{\quad t=2\quad }&\underline{\quad t=3\quad}&\underline{\quad t=4\quad }&\underline{\quad t=5\quad }\\h(t)&191&201&179&125\\g(t)&95.4&127.6&159.8&192\end{array}\right]`

Notice that g(t) is increasing from t=2 to t=5, while h(t) is increasing from t=2 to t=3 and then decreasing.

At t=4, h(t) > g(t)

At t = 5, g(t) > h(t)

therefore, the two lines must intersect at a point between t=4 and t=5.

You can graph this to verify the answer.