- #1
htoor9
- 17
- 0
Homework Statement
Where does the graph of 25x^2 + 16y^2 + 200x - 160y + 400 = 0 have a horizontal tangent line.
Homework Equations
dy/dx dx/dy or something not sure.
The Attempt at a Solution
Well I know that a horizontal tangent line would mean the slope is zero...but what exactly do I do?