# How to find the horizontal distance in this quadratic formula?

• Nov 13th 2012, 04:24 PM
nojnotnow
How to find the horizontal distance in this quadratic formula?
"An archer's arrow follows a parabolic path. The height of the arrow, f(x) in feet, can be modeled by:

f(x) = -0.005x^2 +2x +5 ,

where x is the arrow's horizontal distance in feet."

I've done the quadratic formula and the result didn't seem reasonable..
Is there a specific formula for problems like these?
• Nov 13th 2012, 04:29 PM
skeeter
Re: How to find the horizontal distance in this quadratic formula?
Quote:

Originally Posted by nojnotnow
"An archer's arrow follows a parabolic path. The height of the arrow, f(x) in feet, can be modeled by:

f(x) = -0.005x^2 +2x +5 ,

where x is the arrow's horizontal distance in feet."

I've done the quadratic formula and the result didn't seem reasonable..
Is there a specific formula for problems like these?

My solution seems reasonable ... what did you get?
• Nov 13th 2012, 04:51 PM
nojnotnow
Re: How to find the horizontal distance in this quadratic formula?
I threw the paper away with my work on it already lol

If you don't mind what was your answer and how did you work it out?
• Nov 13th 2012, 04:54 PM
skeeter
Re: How to find the horizontal distance in this quadratic formula?
Quote:

Originally Posted by nojnotnow
I threw the paper away with my work on it already lol

If you don't mind what was your answer and how did you work it out?

f(x) = 0 when it hits the ground. It's just using the quadratic formula ... it's your problem, you work it out.
• Nov 13th 2012, 05:02 PM
nojnotnow
Re: How to find the horizontal distance in this quadratic formula?
I GOT IT, 402.48

I didn't the negative form of the quadratic formula, I just did the positive form which resulted in a negative distance..

That was my bad..