Calculus Examples

$x \frac{d y}{d x} = x - y$

Step 1

Add $y$ to both sides of the equation.

$x \frac{d y}{d x} + y = x$

Step 2

Check if the left side of the equation is the result of the derivative of the term $x y$ .

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Step 2.1

Differentiate using the Product Rule which states that $\frac{d}{d x} [f (x) g (x)]$ is $f (x) \frac{d}{d x} [g (x)] + g (x) \frac{d}{d x} [f (x)]$ where $f (x) = x$ and $g (x) = y$ .

$x \frac{d}{d x} [y] + y \frac{d}{d x} [x]$

Step 2.2

Rewrite $\frac{d}{d x} [y]$ as $y'$ .

$x y' + y \frac{d}{d x} [x]$

Step 2.3

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 1$ .

$x y' + y \cdot 1$

Step 2.4

Substitute $\frac{d y}{d x}$ for $y'$ .

$x \frac{d y}{d x} + y \cdot 1$

Step 2.5

Reorder $y$ and $1$ .

$x \frac{d y}{d x} + 1 \cdot y$

Step 2.6

Multiply $y$ by $1$ .

$x \frac{d y}{d x} + y$

Step 3

Rewrite the left side as a result of differentiating a product.

$\frac{d}{d x} [x y] = x$

Step 4

Set up an integral on each side.

$\int \frac{d}{d x} [x y] d x = \int x d x$

Step 5

Integrate the left side.

$x y = \int x d x$

Step 6

By the Power Rule, the integral of $x$ with respect to $x$ is $\frac{1}{2} x^{2}$ .

$x y = \frac{1}{2} x^{2} + C$

Step 7

Divide each term in $x y = \frac{1}{2} x^{2} + C$ by $x$ and simplify.

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Step 7.1

Divide each term in $x y = \frac{1}{2} x^{2} + C$ by $x$ .

$\frac{x y}{x} = \frac{\frac{1}{2} x^{2}}{x} + \frac{C}{x}$

Step 7.2

Simplify the left side.

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Step 7.2.1

Cancel the common factor of $x$ .

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Step 7.2.1.1

Cancel the common factor.

$\frac{x y}{x} = \frac{\frac{1}{2} x^{2}}{x} + \frac{C}{x}$

Step 7.2.1.2

Divide $y$ by $1$ .

$y = \frac{\frac{1}{2} x^{2}}{x} + \frac{C}{x}$

Step 7.3

Simplify the right side.

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Step 7.3.1

Simplify each term.

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Step 7.3.1.1

Cancel the common factor of $x^{2}$ and $x$ .

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Step 7.3.1.1.1

Factor $x$ out of $\frac{1}{2} x^{2}$ .

$y = \frac{x (\frac{1}{2} x)}{x} + \frac{C}{x}$

Step 7.3.1.1.2

Cancel the common factors.

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Step 7.3.1.1.2.1

Raise $x$ to the power of $1$ .

$y = \frac{x (\frac{1}{2} x)}{x^{1}} + \frac{C}{x}$

Step 7.3.1.1.2.2

Factor $x$ out of $x^{1}$ .

$y = \frac{x (\frac{1}{2} x)}{x \cdot 1} + \frac{C}{x}$

Step 7.3.1.1.2.3

Cancel the common factor.

$y = \frac{x (\frac{1}{2} x)}{x \cdot 1} + \frac{C}{x}$

Step 7.3.1.1.2.4

Rewrite the expression.

$y = \frac{\frac{1}{2} x}{1} + \frac{C}{x}$

Step 7.3.1.1.2.5

Divide $\frac{1}{2} x$ by $1$ .

$y = \frac{1}{2} x + \frac{C}{x}$

Step 7.3.1.2

Combine $\frac{1}{2}$ and $x$ .

$y = \frac{x}{2} + \frac{C}{x}$