Question

Find the time it takes for a rocket following the path h(x)= -2x^2+ 18 to hit the ground

A. 2 seconds
B. 3 seconds
C. 8 seconds
D. 9 seconds

Answer 1

The time it takes for a rocket to hit the ground is 3 seconds

Explanation:

We are given equation for height as

`h(x)=-2x^2+18`

where

x is the time in seconds

When object hits the ground

then height becomes 0

so, we can set h(x)=0

and then we can solve for x

`h(x)=-2x^2+18=0`

Subtract both sides by 18

`-2x^2+18-18=0-18`

`-2x^2=-18`

`x^2=9`

`x=3`

So,

the time it takes for a rocket to hit the ground is 3 seconds