Question

A point moves around the circle x^2 +y^2 = 9. when the point is at (square root of -3, square root of 6) its x coordinate is increasing at the rate of 20 units per second. How fast is the y coordinate changing at that instant?

Answer 1

Find the rate of increase of the function first: \[x^2+y^2=9\\\frac{dx^2}{dt}+\frac{dy^2}{dt}=0\\2xx'+2yy'=0\\y'=\frac{x}{y}x' \]

Answer 2

Then plug all knowns in ;)

Answer 3

im still confused
:/

Answer 4

@sweett2639 Firstly do you know how to take derivative?

Answer 5

First label all our variables and rates.