Calculus Examples

$- x^{2} + x y = 2$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (- x^{2} + x y) = \frac{d}{d x} (2)$

Step 2

Differentiate the left side of the equation.

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Step 2.1

By the Sum Rule, the derivative of $- x^{2} + x y$ with respect to $x$ is $\frac{d}{d x} [- x^{2}] + \frac{d}{d x} [x y]$ .

$\frac{d}{d x} [- x^{2}] + \frac{d}{d x} [x y]$

Step 2.2

Evaluate $\frac{d}{d x} [- x^{2}]$ .

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Step 2.2.1

Since $- 1$ is constant with respect to $x$ , the derivative of $- x^{2}$ with respect to $x$ is $- \frac{d}{d x} [x^{2}]$ .

$- \frac{d}{d x} [x^{2}] + \frac{d}{d x} [x y]$

Step 2.2.2

Differentiate using the Power Rule which states that $\frac{d}{d x} [x^{n}]$ is $n x^{n - 1}$ where $n = 2$ .

$- (2 x) + \frac{d}{d x} [x y]$

Step 2.2.3

Multiply $2$ by $- 1$ .

$- 2 x + \frac{d}{d x} [x y]$

Step 2.3

Evaluate $\frac{d}{d x} [x y]$ .

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Step 2.3.1

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 $g (x) = y$ .

$- 2 x + x \frac{d}{d x} [y] + y \frac{d}{d x} [x]$

Step 2.3.2

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

$- 2 x + x y' + y \frac{d}{d x} [x]$

Step 2.3.3

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

$- 2 x + x y' + y \cdot 1$

Step 2.3.4

Multiply $y$ by $1$ .

$- 2 x + x y' + y$

Step 2.4

Reorder terms.

$x y' - 2 x + y$

Step 3

Since $2$ is constant with respect to $x$ , the derivative of $2$ with respect to $x$ is $0$ .

$0$

Step 4

Reform the equation by setting the left side equal to the right side.

$x y' - 2 x + y = 0$

Step 5

Solve for $y'$ .

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Step 5.1

Move all terms not containing $y'$ to the right side of the equation.

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Step 5.1.1

Add $2 x$ to both sides of the equation.

$x y' + y = 2 x$

Step 5.1.2

Subtract $y$ from both sides of the equation.

$x y' = 2 x - y$

Step 5.2

Divide each term in $x y' = 2 x - y$ by $x$ and simplify.

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Step 5.2.1

Divide each term in $x y' = 2 x - y$ by $x$ .

$\frac{x y'}{x} = \frac{2 x}{x} + \frac{- y}{x}$

Step 5.2.2

Simplify the left side.

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Step 5.2.2.1

Cancel the common factor of $x$ .

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Step 5.2.2.1.1

Cancel the common factor.

$\frac{x y'}{x} = \frac{2 x}{x} + \frac{- y}{x}$

Step 5.2.2.1.2

Divide $y'$ by $1$ .

$y' = \frac{2 x}{x} + \frac{- y}{x}$

Step 5.2.3

Simplify the right side.

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Step 5.2.3.1

Simplify each term.

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Step 5.2.3.1.1

Cancel the common factor of $x$ .

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Step 5.2.3.1.1.1

Cancel the common factor.

$y' = \frac{2 x}{x} + \frac{- y}{x}$

Step 5.2.3.1.1.2

Divide $2$ by $1$ .

$y' = 2 + \frac{- y}{x}$

Step 5.2.3.1.2

Move the negative in front of the fraction.

$y' = 2 - \frac{y}{x}$

Step 6

Replace $y'$ with $\frac{d y}{d x}$ .

$\frac{d y}{d x} = 2 - \frac{y}{x}$