Calculus Examples

$f (x) = \frac{1 - x^{2}}{1 + x^{2}}$

Step 1

Differentiate using the Quotient Rule which states that $\frac{d}{d x} [\frac{f (x)}{g (x)}]$ is $\frac{g (x) \frac{d}{d x} [f (x)] - f (x) \frac{d}{d x} [g (x)]}{{g (x)}^{2}}$ where $f (x) = 1 - x^{2}$ and $g (x) = 1 + x^{2}$ .

$\frac{(1 + x^{2}) \frac{d}{d x} [1 - x^{2}] - (1 - x^{2}) \frac{d}{d x} [1 + x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2

Differentiate.

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Step 2.1

By the Sum Rule, the derivative of $1 - x^{2}$ with respect to $x$ is $\frac{d}{d x} [1] + \frac{d}{d x} [- x^{2}]$ .

$\frac{(1 + x^{2}) (\frac{d}{d x} [1] + \frac{d}{d x} [- x^{2}]) - (1 - x^{2}) \frac{d}{d x} [1 + x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2.2

Since $1$ is constant with respect to $x$ , the derivative of $1$ with respect to $x$ is $0$ .

$\frac{(1 + x^{2}) (0 + \frac{d}{d x} [- x^{2}]) - (1 - x^{2}) \frac{d}{d x} [1 + x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2.3

Add $0$ and $\frac{d}{d x} [- x^{2}]$ .

$\frac{(1 + x^{2}) \frac{d}{d x} [- x^{2}] - (1 - x^{2}) \frac{d}{d x} [1 + x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2.4

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

$\frac{(1 + x^{2}) (- \frac{d}{d x} [x^{2}]) - (1 - x^{2}) \frac{d}{d x} [1 + x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2.5

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

$\frac{(1 + x^{2}) (- (2 x)) - (1 - x^{2}) \frac{d}{d x} [1 + x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2.6

Multiply $2$ by $- 1$ .

$\frac{(1 + x^{2}) (- 2 x) - (1 - x^{2}) \frac{d}{d x} [1 + x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2.7

By the Sum Rule, the derivative of $1 + x^{2}$ with respect to $x$ is $\frac{d}{d x} [1] + \frac{d}{d x} [x^{2}]$ .

$\frac{(1 + x^{2}) (- 2 x) - (1 - x^{2}) (\frac{d}{d x} [1] + \frac{d}{d x} [x^{2}])}{{(1 + x^{2})}^{2}}$

Step 2.8

Since $1$ is constant with respect to $x$ , the derivative of $1$ with respect to $x$ is $0$ .

$\frac{(1 + x^{2}) (- 2 x) - (1 - x^{2}) (0 + \frac{d}{d x} [x^{2}])}{{(1 + x^{2})}^{2}}$

Step 2.9

Add $0$ and $\frac{d}{d x} [x^{2}]$ .

$\frac{(1 + x^{2}) (- 2 x) - (1 - x^{2}) \frac{d}{d x} [x^{2}]}{{(1 + x^{2})}^{2}}$

Step 2.10

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

$\frac{(1 + x^{2}) (- 2 x) - (1 - x^{2}) (2 x)}{{(1 + x^{2})}^{2}}$

Step 2.11

Multiply $2$ by $- 1$ .

$\frac{(1 + x^{2}) (- 2 x) - 2 (1 - x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3

Simplify.

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Step 3.1

Apply the distributive property.

$\frac{1 (- 2 x) + x^{2} (- 2 x) - 2 (1 - x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.2

Apply the distributive property.

$\frac{1 (- 2 x) + x^{2} (- 2 x) + (- 2 \cdot 1 - 2 (- x^{2})) x}{{(1 + x^{2})}^{2}}$

Step 3.3

Apply the distributive property.

$\frac{1 (- 2 x) + x^{2} (- 2 x) - 2 \cdot 1 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4

Simplify the numerator.

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Step 3.4.1

Simplify each term.

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Step 3.4.1.1

Multiply $- 2 x$ by $1$ .

$\frac{- 2 x + x^{2} (- 2 x) - 2 \cdot 1 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4.1.2

Rewrite using the commutative property of multiplication.

$\frac{- 2 x - 2 x^{2} x - 2 \cdot 1 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4.1.3

Multiply $x^{2}$ by $x$ by adding the exponents.

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Step 3.4.1.3.1

Move $x$ .

$\frac{- 2 x - 2 (x \cdot x^{2}) - 2 \cdot 1 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4.1.3.2

Multiply $x$ by $x^{2}$ .

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Step 3.4.1.3.2.1

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

$\frac{- 2 x - 2 (x^{1} x^{2}) - 2 \cdot 1 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4.1.3.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{- 2 x - 2 x^{1 + 2} - 2 \cdot 1 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4.1.3.3

Add $1$ and $2$ .

$\frac{- 2 x - 2 x^{3} - 2 \cdot 1 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4.1.4

Multiply $- 2$ by $1$ .

$\frac{- 2 x - 2 x^{3} - 2 x - 2 (- x^{2}) x}{{(1 + x^{2})}^{2}}$

Step 3.4.1.5

Multiply $x^{2}$ by $x$ by adding the exponents.

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Step 3.4.1.5.1

Move $x$ .

$\frac{- 2 x - 2 x^{3} - 2 x - 2 (- (x \cdot x^{2}))}{{(1 + x^{2})}^{2}}$

Step 3.4.1.5.2

Multiply $x$ by $x^{2}$ .

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Step 3.4.1.5.2.1

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

$\frac{- 2 x - 2 x^{3} - 2 x - 2 (- (x^{1} x^{2}))}{{(1 + x^{2})}^{2}}$

Step 3.4.1.5.2.2

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{- 2 x - 2 x^{3} - 2 x - 2 (- x^{1 + 2})}{{(1 + x^{2})}^{2}}$

Step 3.4.1.5.3

Add $1$ and $2$ .

$\frac{- 2 x - 2 x^{3} - 2 x - 2 (- x^{3})}{{(1 + x^{2})}^{2}}$

Step 3.4.1.6

Multiply $- 1$ by $- 2$ .

$\frac{- 2 x - 2 x^{3} - 2 x + 2 x^{3}}{{(1 + x^{2})}^{2}}$

Step 3.4.2

Combine the opposite terms in $- 2 x - 2 x^{3} - 2 x + 2 x^{3}$ .

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Step 3.4.2.1

Add $- 2 x^{3}$ and $2 x^{3}$ .

$\frac{- 2 x - 2 x + 0}{{(1 + x^{2})}^{2}}$

Step 3.4.2.2

Add $- 2 x - 2 x$ and $0$ .

$\frac{- 2 x - 2 x}{{(1 + x^{2})}^{2}}$

Step 3.4.3

Subtract $2 x$ from $- 2 x$ .

$\frac{- 4 x}{{(1 + x^{2})}^{2}}$

Step 3.5

Move the negative in front of the fraction.

$- \frac{4 x}{{(1 + x^{2})}^{2}}$