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45 votes
Need help with 9th-grade math. Algebra 1

A ball is thrown in the air. The path of the ball is represented by the equation h=-t^2+8t, where t represents time in seconds and h represents the height of the ball in meters.

What is the maximum height of the ball?

How long is the ball in the air for before it hits the ground?

User Toria
by
2.9k points

2 Answers

17 votes
17 votes

Answer:

y are you ga

Explanation:

User ElRudi
by
3.0k points
25 votes
25 votes

Answer:

a) 16 meters ; b) 8 seconds

Explanation:

The function can be represent with a parabola whose vertex is its maximum point

for answer the first question we have to find the y of the vertex

first of all we have to find the x

Vertex (x) = -b/2a = -8/-2 = 4

if we substitute t with 4, we can find the y

Vertex (y) = -(4^2) + (8*4) =

= -16 + 32 = 16

so the answer is 16 meters

for answer the second question we have to find where the parabola intercepts the x axis, that means solve the associated equation:

-t^2 + 8t = 0

t^2-8t = 0

t(t-8) = 0

t = 0

t = 8

the parabola intercept the x axis in (0,0) and in (8,0)

if we find the distance between this two points we can answer to the question

8-0 = 8 seconds

User Bitbang
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3.3k points