Question

Mark for Review

2 A plece of paper was dropped from the top of a tall building. The height of the plece of paper above the
ground can be found using the function y = -2.5x + 30, where x is the time in seconds the plece of paper
has been in the air.
11
20
15
10
5
17 18 2017 2016
-10
-15
-30
How many seconds did It take the plece of paper to reach the ground?
Record your answer and fill in the bubbles on your answer document.

Answer 1

12 seconds

Explanation:

Given

`y = -2.5x + 30`

Required

Determine the time taken to reach the ground

For the paper to reach the ground, y = 0

So, we have:

`y = -2.5x + 30`

`0 = -2.5x + 30`

Collect Like Terms

`2.5x +0 = 30`

`2.5x = 30`

Divide through by 2.5

`2.5x/2.5 = 30/2.5`

`x = 30/2.5`

`x = 12`

Hence:

Time taken is 12 seconds