- #1

jgens

Gold Member

- 1,593

- 50

## Homework Statement

A particle moves along a path described by y = 4 - x^2. At what point along the curve are x and y changing at the same rate

## Homework Equations

Simple equations regarding derivatives.

## The Attempt at a Solution

It's been a while before I've done any related rates problems, could someone please let me know if this is correct:

Since, x and y must be changing at the same rate (presumably with respect to time) x' = y' and y' = -2xx'. Therefore, -2x = 1 and x = -1/2. Placing my x value into the original equation yields 15/4. Hence, the point is (-1/2, 15/4).

Thanks.