Calculus Examples

$y = (1 + x^{2}) \tan (x - y)$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d x} (y) = \frac{d}{d x} ((1 + x^{2}) \tan (x - y))$

Step 2

The derivative of $y$ with respect to $x$ is $y'$ .

$y'$

Step 3

Differentiate the right side of the equation.

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Step 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 $f (x) = 1 + x^{2}$ and $g (x) = \tan (x - y)$ .

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

Step 3.2

Differentiate using the chain rule, which states that $\frac{d}{d x} [f (g (x))]$ is $f' (g (x)) g' (x)$ where $f (x) = \tan (x)$ and $g (x) = x - y$ .

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Step 3.2.1

To apply the Chain Rule, set $u$ as $x - y$ .

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

Step 3.2.2

The derivative of $\tan (u)$ with respect to $u$ is $\sec^{2} (u)$ .

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

Step 3.2.3

Replace all occurrences of $u$ with $x - y$ .

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

Step 3.3

Differentiate.

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Step 3.3.1

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

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

Step 3.3.2

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

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

Step 3.3.3

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

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

Step 3.4

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

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

Step 3.5

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

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

Step 3.6

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

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

Step 3.7

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

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

Step 3.8

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

$(1 + x^{2}) \sec^{2} (x - y) (1 - y') + \tan (x - y) (2 x)$

Step 3.9

Reorder terms.

$\sec^{2} (x - y) (1 + x^{2}) (1 - y') + 2 x \tan (x - y)$

Step 4

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

$y' = \sec^{2} (x - y) (1 + x^{2}) (1 - y') + 2 x \tan (x - y)$

Step 5

Solve for $y'$ .

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Step 5.1

Simplify the right side.

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Step 5.1.1

Simplify $\sec^{2} (x - y) (1 + x^{2}) (1 - y') + 2 x \tan (x - y)$ .

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Step 5.1.1.1

Simplify each term.

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Step 5.1.1.1.1

Apply the distributive property.

$y' = (\sec^{2} (x - y) \cdot 1 + \sec^{2} (x - y) x^{2}) (1 - y') + 2 x \tan (x - y)$

Step 5.1.1.1.2

Multiply $\sec^{2} (x - y)$ by $1$ .

$y' = (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2}) (1 - y') + 2 x \tan (x - y)$

Step 5.1.1.1.3

Expand $(\sec^{2} (x - y) + \sec^{2} (x - y) x^{2}) (1 - y')$ using the FOIL Method.

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Step 5.1.1.1.3.1

Apply the distributive property.

$y' = \sec^{2} (x - y) (1 - y') + \sec^{2} (x - y) x^{2} (1 - y') + 2 x \tan (x - y)$

Step 5.1.1.1.3.2

Apply the distributive property.

$y' = \sec^{2} (x - y) \cdot 1 + \sec^{2} (x - y) (- y') + \sec^{2} (x - y) x^{2} (1 - y') + 2 x \tan (x - y)$

Step 5.1.1.1.3.3

Apply the distributive property.

$y' = \sec^{2} (x - y) \cdot 1 + \sec^{2} (x - y) (- y') + \sec^{2} (x - y) x^{2} \cdot 1 + \sec^{2} (x - y) x^{2} (- y') + 2 x \tan (x - y)$

Step 5.1.1.1.4

Simplify each term.

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Step 5.1.1.1.4.1

Multiply $\sec^{2} (x - y)$ by $1$ .

$y' = \sec^{2} (x - y) + \sec^{2} (x - y) (- y') + \sec^{2} (x - y) x^{2} \cdot 1 + \sec^{2} (x - y) x^{2} (- y') + 2 x \tan (x - y)$

Step 5.1.1.1.4.2

Rewrite using the commutative property of multiplication.

$y' = \sec^{2} (x - y) - \sec^{2} (x - y) y' + \sec^{2} (x - y) x^{2} \cdot 1 + \sec^{2} (x - y) x^{2} (- y') + 2 x \tan (x - y)$

Step 5.1.1.1.4.3

Multiply $\sec^{2} (x - y)$ by $1$ .

$y' = \sec^{2} (x - y) - \sec^{2} (x - y) y' + x^{2} \cdot \sec^{2} (x - y) + \sec^{2} (x - y) x^{2} (- y') + 2 x \tan (x - y)$

Step 5.1.1.1.4.4

Rewrite using the commutative property of multiplication.

$y' = \sec^{2} (x - y) - \sec^{2} (x - y) y' + x^{2} \sec^{2} (x - y) - \sec^{2} (x - y) x^{2} y' + 2 x \tan (x - y)$

Step 5.1.1.2

Reorder factors in $\sec^{2} (x - y) - \sec^{2} (x - y) y' + x^{2} \sec^{2} (x - y) - \sec^{2} (x - y) x^{2} y' + 2 x \tan (x - y)$ .

$y' = \sec^{2} (x - y) - y' \sec^{2} (x - y) + x^{2} \sec^{2} (x - y) - x^{2} y' \sec^{2} (x - y) + 2 x \tan (x - y)$

Step 5.2

Since $y'$ is on the right side of the equation, switch the sides so it is on the left side of the equation.

$\sec^{2} (x - y) - y' \sec^{2} (x - y) + x^{2} \sec^{2} (x - y) - x^{2} y' \sec^{2} (x - y) + 2 x \tan (x - y) = y'$

Step 5.3

Subtract $y'$ from both sides of the equation.

$\sec^{2} (x - y) - y' \sec^{2} (x - y) + x^{2} \sec^{2} (x - y) - x^{2} y' \sec^{2} (x - y) + 2 x \tan (x - y) - y' = 0$

Step 5.4

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

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Step 5.4.1

Subtract $\sec^{2} (x - y)$ from both sides of the equation.

$- y' \sec^{2} (x - y) + x^{2} \sec^{2} (x - y) - x^{2} y' \sec^{2} (x - y) + 2 x \tan (x - y) - y' = - \sec^{2} (x - y)$

Step 5.4.2

Subtract $x^{2} \sec^{2} (x - y)$ from both sides of the equation.

$- y' \sec^{2} (x - y) - x^{2} y' \sec^{2} (x - y) + 2 x \tan (x - y) - y' = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y)$

Step 5.4.3

Subtract $2 x \tan (x - y)$ from both sides of the equation.

$- y' \sec^{2} (x - y) - x^{2} y' \sec^{2} (x - y) - y' = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$

Step 5.5

Factor $y'$ out of $- y' \sec^{2} (x - y) - x^{2} y' \sec^{2} (x - y) - y'$ .

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Step 5.5.1

Factor $y'$ out of $- y' \sec^{2} (x - y)$ .

$y' (- 1 \sec^{2} (x - y)) - x^{2} y' \sec^{2} (x - y) - y' = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$

Step 5.5.2

Factor $y'$ out of $- x^{2} y' \sec^{2} (x - y)$ .

$y' (- 1 \sec^{2} (x - y)) + y' (- x^{2} \sec^{2} (x - y)) - y' = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$

Step 5.5.3

Factor $y'$ out of $- y'$ .

$y' (- 1 \sec^{2} (x - y)) + y' (- x^{2} \sec^{2} (x - y)) + y' \cdot - 1 = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$

Step 5.5.4

Factor $y'$ out of $y' (- 1 \sec^{2} (x - y)) + y' (- x^{2} \sec^{2} (x - y))$ .

$y' (- 1 \sec^{2} (x - y) - x^{2} \sec^{2} (x - y)) + y' \cdot - 1 = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$

Step 5.5.5

Factor $y'$ out of $y' (- 1 \sec^{2} (x - y) - x^{2} \sec^{2} (x - y)) + y' \cdot - 1$ .

$y' (- 1 \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1) = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$

Step 5.6

Rewrite $- 1 \sec^{2} (x - y)$ as $- \sec^{2} (x - y)$ .

$y' (- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1) = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$

Step 5.7

Divide each term in $y' (- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1) = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$ by $- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1$ and simplify.

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Step 5.7.1

Divide each term in $y' (- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1) = - \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 2 x \tan (x - y)$ by $- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1$ .

$\frac{y' (- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} = \frac{- \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} + \frac{- x^{2} \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} + \frac{- 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.2

Simplify the left side.

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Step 5.7.2.1

Cancel the common factor of $- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1$ .

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Step 5.7.2.1.1

Cancel the common factor.

Step 5.7.2.1.2

Divide $y'$ by $1$ .

$y' = \frac{- \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} + \frac{- x^{2} \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} + \frac{- 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3

Simplify the right side.

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Step 5.7.3.1

Simplify terms.

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Step 5.7.3.1.1

Simplify each term.

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Step 5.7.3.1.1.1

Move the negative in front of the fraction.

$y' = - \frac{\sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} + \frac{- x^{2} \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} + \frac{- 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.1.1.2

Move the negative in front of the fraction.

$y' = - \frac{\sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} - \frac{x^{2} \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} + \frac{- 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.1.1.3

Move the negative in front of the fraction.

$y' = - \frac{\sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} - \frac{x^{2} \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} - \frac{2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.1.2

Simplify terms.

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Step 5.7.3.1.2.1

Combine the numerators over the common denominator.

$y' = \frac{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} - \frac{2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.1.2.2

Factor $\sec^{2} (x - y)$ out of $- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y)$ .

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Step 5.7.3.1.2.2.1

Factor $\sec^{2} (x - y)$ out of $- \sec^{2} (x - y)$ .

$y' = \frac{\sec^{2} (x - y) \cdot - 1 - x^{2} \sec^{2} (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} - \frac{2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.1.2.2.2

Factor $\sec^{2} (x - y)$ out of $- x^{2} \sec^{2} (x - y)$ .

$y' = \frac{\sec^{2} (x - y) \cdot - 1 + \sec^{2} (x - y) (- x^{2})}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} - \frac{2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.1.2.2.3

Factor $\sec^{2} (x - y)$ out of $\sec^{2} (x - y) \cdot - 1 + \sec^{2} (x - y) (- x^{2})$ .

$y' = \frac{\sec^{2} (x - y) (- 1 - x^{2})}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1} - \frac{2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.1.2.3

Combine the numerators over the common denominator.

$y' = \frac{\sec^{2} (x - y) (- 1 - x^{2}) - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.2

Simplify the numerator.

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Step 5.7.3.2.1

Apply the distributive property.

$y' = \frac{\sec^{2} (x - y) \cdot - 1 + \sec^{2} (x - y) (- x^{2}) - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.2.2

Move $- 1$ to the left of $\sec^{2} (x - y)$ .

$y' = \frac{- 1 \cdot \sec^{2} (x - y) + \sec^{2} (x - y) (- x^{2}) - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.2.3

Rewrite using the commutative property of multiplication.

$y' = \frac{- 1 \cdot \sec^{2} (x - y) - \sec^{2} (x - y) x^{2} - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.2.4

Rewrite $- 1 \sec^{2} (x - y)$ as $- \sec^{2} (x - y)$ .

$y' = \frac{- \sec^{2} (x - y) - \sec^{2} (x - y) x^{2} - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3

Simplify terms.

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Step 5.7.3.3.1

Factor $- 1$ out of $- \sec^{2} (x - y)$ .

$y' = \frac{- (\sec^{2} (x - y)) - \sec^{2} (x - y) x^{2} - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3.2

Factor $- 1$ out of $- \sec^{2} (x - y) x^{2}$ .

$y' = \frac{- (\sec^{2} (x - y)) - (\sec^{2} (x - y) x^{2}) - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3.3

Factor $- 1$ out of $- (\sec^{2} (x - y)) - (\sec^{2} (x - y) x^{2})$ .

$y' = \frac{- (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2}) - 2 x \tan (x - y)}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3.4

Factor $- 1$ out of $- 2 x \tan (x - y)$ .

$y' = \frac{- (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2}) - (2 x \tan (x - y))}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3.5

Factor $- 1$ out of $- (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2}) - (2 x \tan (x - y))$ .

$y' = \frac{- (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3.6

Rewrite $- (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))$ as $- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))$ .

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- \sec^{2} (x - y) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3.7

Factor $- 1$ out of $- \sec^{2} (x - y)$ .

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- (\sec^{2} (x - y)) - x^{2} \sec^{2} (x - y) - 1}$

Step 5.7.3.3.8

Factor $- 1$ out of $- x^{2} \sec^{2} (x - y)$ .

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- (\sec^{2} (x - y)) - (x^{2} \sec^{2} (x - y)) - 1}$

Step 5.7.3.3.9

Factor $- 1$ out of $- (\sec^{2} (x - y)) - (x^{2} \sec^{2} (x - y))$ .

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y)) - 1}$

Step 5.7.3.3.10

Rewrite $- 1$ as $- 1 (1)$ .

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y)) - 1 (1)}$

Step 5.7.3.3.11

Factor $- 1$ out of $- (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y)) - 1 (1)$ .

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1)}$

Step 5.7.3.3.12

Rewrite $- (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1)$ as $- 1 (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1)$ .

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- 1 (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1)}$

Step 5.7.3.3.13

Cancel the common factor.

$y' = \frac{- 1 (\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y))}{- 1 (\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1)}$

Step 5.7.3.3.14

Rewrite the expression.

$y' = \frac{\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y)}{\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1}$

Step 5.7.3.3.15

Reorder factors in $\frac{\sec^{2} (x - y) + \sec^{2} (x - y) x^{2} + 2 x \tan (x - y)}{\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1}$ .

$y' = \frac{\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 2 x \tan (x - y)}{\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1}$

Step 6

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

$\frac{d y}{d x} = \frac{\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 2 x \tan (x - y)}{\sec^{2} (x - y) + x^{2} \sec^{2} (x - y) + 1}$