If x^2 + y^2 = 25 and dx/dt = 8, find dy/dt when x=3.
when x=3, y=4
2x dx/dt + 2y dy/dt = 0
or, losing the factor of 2,
x dx/dt + y dy/dt = 0
Now just plug in your numbers.
2x dx/dt + 2y dy/dt = 0
or, losing the factor of 2,
x dx/dt + y dy/dt = 0
Now just plug in your numbers.