Homework Help

When a ball is thrown into the air, its height depends on the time since the ball was...

user profile pic

user1074408 | Student, Grade 10 | (Level 1) eNoter

Posted March 21, 2013 at 2:07 AM via web

dislike 2 like

When a ball is thrown into the air, its height depends on the time since the ball was thrown. The equation for its height is h=-t raised to the power 2 + 2t + 3. Find the greatest height attained by the ball.

A. 1 foot
B. 4 feet
C. 5 feet
D. 3 feet

1 Answer | Add Yours

user profile pic

violy | High School Teacher | (Level 3) Assistant Educator

Posted March 21, 2013 at 2:26 AM (Answer #1)

dislike 1 like

Take note that the equation is in the form h(t) = at^2 +bt + c. 

Here, a < 0 so the parabola opens upward. Therefore, the maximum height can be found on the ordinate of the vertex. 

We will solve for h = -b/2a first. 

`h = -b/(2a) = - (2)/(2*-1) = -2/-2 = 1.`

Solving for the ordinate of the vertex (k) by plugging-in t = 1 on the given function. 

`k = -(1)^2 + 2(1) + 3 = -1 + 2 + 3 = 4ft`

Hence, the greatest height attained by the ball is 4 feet.

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes