
Mark H. answered 01/14/20
Tutoring in Math and Science at all levels
x2 + 3y2 = 12
Assuming that x and y are both functions of t:
2x*(dx/dt) + 6y*(dy/dt) = 0
dy/dt = 2x/6y * dx/dt
When y = 1, x = +/- 3 Using this, and dx/dt = 0, dy/dx = +/- 2
I assume that the answer is #3) dy/dt = -2. I'm not sure why!! (EDIT: What I meant was why not +2 and -2...)