Question

A rocket is launched from the ground. The quadratic function y=-16x2+56x models the rockets height in feet above the ground after x seconds. About how long is the rocket in the air

Answer 1

Therefore,

3.5 s long was the rocket in the air.

Explanation:

Given:

A rocket is launched from the ground.

Height function for Rocket is given as

`y=-16x^(2)+56x`

Where,

y = height in function with x as time in second

To Find:

How long is the rocket in the air, x =?

Solution:

Expression is given

`y=-16x^(2)+56x`

So for time in air put y = 0 in above Expression

`0=-16x^(2)+56x`

`16x^(2)-56x=0\\16x(x-3.5)=0\\16x=0\ or\ x-3.5 = 0\\x=0\ or\ x= 3.5`

x cannot be negative

∴ x = 3.5 sec.

Therefore,

3.5 s long was the rocket in the air.