Partial Differentiation with Exercises and Solutions

Definition of Derivative

Example 1: Derivative of f(x) with respect to x:

\[ \frac{df}{dx}(x) = \lim_{\Delta x \to 0} \frac{f(x + \Delta x) - f(x)}{\Delta x} \]

Partial Differentiation

Partial derivative of f(x,y) with respect to x:

\[ \frac{\partial f}{\partial x}(x, y) = \lim_{\Delta x \to 0} \frac{f(x + \Delta x, y) - f(x, y)}{\Delta x} \]

Partial derivative of f(x,y) with respect to y:

\[ \frac{\partial f}{\partial y}(x, y) = \lim_{\Delta y \to 0} \frac{f(x, y + \Delta y) - f(x, y)}{\Delta y} \]

Example 1:

\[ f(x, y) = e^{-(x^{2} + y^{2})} \]

Question: Find the partial derivative with respect to x.

Solution 1

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Example 2:

\[ f(x, y) = -(x-3)^{2} + xy + 16 \]

Find the partial derivative with respect to x.

Solution 2

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Partial differentiation: Practical Questions

Example 3: Calculate all first and second order partial derivatives of:

\[ f(x, y) = e^{(3x^{2}y)} \]

Solution 3

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Additional partial derivative with respect to x and y

Example 4:

\[ f(x, y) = x / y \]

Solution 4

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Example 5:

\[ f(x, y) = - (x-3y)^{2} \]

Solution 5

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Example 6:

\[ f(x, y) = e^{(2x+y^{3})} \]

Solution 6

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Example 7:

\[ f(x, y) = xln(2y) \]

Solution 7

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Example 8:

\[ f(x, y) = cos(x(e^{3x})) \]

Solution 8

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