Applying Implicit Differentiation
Finding the slope of a tangent line at specific points becomes straightforward once you've found dy/dx. For example, with the equation x² + 4y² = 4, first differentiate to get 2x + 8y · dy/dx = 0, which simplifies to dy/dx = -x/(4y).
To evaluate the slope at a point like (√2, -√2), just substitute those coordinates into your derivative formula. At this point, dy/dx = -√2/4(−√2) = 1/2.
We can also find higher-order derivatives implicitly. For the circle x² + y² = 25, we first find dy/dx = -x/y. To find d²y/dx², we differentiate dy/dx with respect to x, applying the quotient rule. At the point (4,3), this gives us d²y/dx² = -25/27.
🔑 Remember: When finding a derivative at a specific point, always calculate the derivative formula first, then substitute the point's coordinates.