Calculus Examples

$h (u) = (u - \sqrt{u}) (u + \sqrt{u})$

Step 1

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

$(u - \sqrt{u}) \frac{d}{d u} [u + \sqrt{u}] + (u + \sqrt{u}) \frac{d}{d u} [u - \sqrt{u}]$

Step 2

Differentiate.

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Step 2.1

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

$(u - \sqrt{u}) (\frac{d}{d u} [u] + \frac{d}{d u} [\sqrt{u}]) + (u + \sqrt{u}) \frac{d}{d u} [u - \sqrt{u}]$

Step 2.2

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

$(u - \sqrt{u}) (1 + \frac{d}{d u} [\sqrt{u}]) + (u + \sqrt{u}) \frac{d}{d u} [u - \sqrt{u}]$

Step 3

Evaluate $\frac{d}{d u} [\sqrt{u}]$ .

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Step 3.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{u}$ as $u^{\frac{1}{2}}$ .

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

Step 3.2

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

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

Step 3.3

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

$(u - \sqrt{u}) (1 + \frac{1}{2} u^{\frac{1}{2} - 1 \cdot \frac{2}{2}}) + (u + \sqrt{u}) \frac{d}{d u} [u - \sqrt{u}]$

Step 3.4

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

$(u - \sqrt{u}) (1 + \frac{1}{2} u^{\frac{1}{2} + \frac{- 1 \cdot 2}{2}}) + (u + \sqrt{u}) \frac{d}{d u} [u - \sqrt{u}]$

Step 3.5

Combine the numerators over the common denominator.

$(u - \sqrt{u}) (1 + \frac{1}{2} u^{\frac{1 - 1 \cdot 2}{2}}) + (u + \sqrt{u}) \frac{d}{d u} [u - \sqrt{u}]$

Step 3.6

Simplify the numerator.

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Step 3.6.1

Multiply $- 1$ by $2$ .

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

Step 3.6.2

Subtract $2$ from $1$ .

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

Step 3.7

Move the negative in front of the fraction.

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

Step 4

Simplify.

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Step 4.1

Rewrite the expression using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$(u - \sqrt{u}) (1 + \frac{1}{2} \cdot \frac{1}{u^{\frac{1}{2}}}) + (u + \sqrt{u}) \frac{d}{d u} [u - \sqrt{u}]$

Step 4.2

Multiply $\frac{1}{2}$ by $\frac{1}{u^{\frac{1}{2}}}$ .

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

Step 5

Differentiate.

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Step 5.1

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

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

Step 5.2

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

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

Step 6

Evaluate $\frac{d}{d u} [- \sqrt{u}]$ .

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Step 6.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{u}$ as $u^{\frac{1}{2}}$ .

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

Step 6.2

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

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

Step 6.3

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

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

Step 6.4

To write $- 1$ as a fraction with a common denominator, multiply by $\frac{2}{2}$ .

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

Step 6.5

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

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

Step 6.6

Combine the numerators over the common denominator.

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

Step 6.7

Simplify the numerator.

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Step 6.7.1

Multiply $- 1$ by $2$ .

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

Step 6.7.2

Subtract $2$ from $1$ .

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

Step 6.8

Move the negative in front of the fraction.

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

Step 6.9

Combine $\frac{1}{2}$ and $u^{- \frac{1}{2}}$ .

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

Step 6.10

Move $u^{- \frac{1}{2}}$ to the denominator using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

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

Step 7

Simplify.

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Step 7.1

Reorder terms.

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

Step 7.2

Simplify each term.

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Step 7.2.1

Expand $(1 + \frac{1}{2 u^{\frac{1}{2}}}) (u - \sqrt{u})$ using the FOIL Method.

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Step 7.2.1.1

Apply the distributive property.

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

Step 7.2.1.2

Apply the distributive property.

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

Step 7.2.1.3

Apply the distributive property.

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

Step 7.2.2

Simplify each term.

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Step 7.2.2.1

Multiply $u$ by $1$ .

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

Step 7.2.2.2

Multiply $- \sqrt{u}$ by $1$ .

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

Step 7.2.2.3

Combine $\frac{1}{2 u^{\frac{1}{2}}}$ and $u$ .

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

Step 7.2.2.4

Move $u^{\frac{1}{2}}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

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

Step 7.2.2.5

Multiply $u$ by $u^{- \frac{1}{2}}$ by adding the exponents.

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Step 7.2.2.5.1

Multiply $u$ by $u^{- \frac{1}{2}}$ .

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Step 7.2.2.5.1.1

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

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

Step 7.2.2.5.1.2

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

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

Step 7.2.2.5.2

Write $1$ as a fraction with a common denominator.

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

Step 7.2.2.5.3

Combine the numerators over the common denominator.

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

Step 7.2.2.5.4

Subtract $1$ from $2$ .

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

Step 7.2.2.6

Rewrite using the commutative property of multiplication.

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

Step 7.2.2.7

Combine $\sqrt{u}$ and $\frac{1}{2 u^{\frac{1}{2}}}$ .

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

Step 7.2.3

Expand $(1 - \frac{1}{2 u^{\frac{1}{2}}}) (u + \sqrt{u})$ using the FOIL Method.

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Step 7.2.3.1

Apply the distributive property.

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

Step 7.2.3.2

Apply the distributive property.

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

Step 7.2.3.3

Apply the distributive property.

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + 1 u + 1 \sqrt{u} - \frac{1}{2 u^{\frac{1}{2}}} u - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4

Simplify each term.

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Step 7.2.4.1

Multiply $u$ by $1$ .

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + 1 \sqrt{u} - \frac{1}{2 u^{\frac{1}{2}}} u - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.2

Multiply $\sqrt{u}$ by $1$ .

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{1}{2 u^{\frac{1}{2}}} u - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.3

Combine $u$ and $\frac{1}{2 u^{\frac{1}{2}}}$ .

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u}{2 u^{\frac{1}{2}}} - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.4

Move $u^{\frac{1}{2}}$ to the numerator using the negative exponent rule $\frac{1}{b^{n}} = b^{- n}$ .

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u \cdot u^{- \frac{1}{2}}}{2} - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.5

Multiply $u$ by $u^{- \frac{1}{2}}$ by adding the exponents.

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Step 7.2.4.5.1

Multiply $u$ by $u^{- \frac{1}{2}}$ .

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Step 7.2.4.5.1.1

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

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u^{1} u^{- \frac{1}{2}}}{2} - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.5.1.2

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

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u^{1 - \frac{1}{2}}}{2} - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.5.2

Write $1$ as a fraction with a common denominator.

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u^{\frac{2}{2} - \frac{1}{2}}}{2} - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.5.3

Combine the numerators over the common denominator.

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u^{\frac{2 - 1}{2}}}{2} - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.5.4

Subtract $1$ from $2$ .

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u^{\frac{1}{2}}}{2} - \frac{1}{2 u^{\frac{1}{2}}} \sqrt{u}$

Step 7.2.4.6

Combine $\sqrt{u}$ and $\frac{1}{2 u^{\frac{1}{2}}}$ .

$u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}}$

Step 7.3

Combine the opposite terms in $u - \sqrt{u} + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u + \sqrt{u} - \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}}$ .

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Step 7.3.1

Add $- \sqrt{u}$ and $\sqrt{u}$ .

$u + 0 + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u - \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}}$

Step 7.3.2

Add $u$ and $0$ .

$u + \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u - \frac{u^{\frac{1}{2}}}{2} - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}}$

Step 7.3.3

Subtract $\frac{u^{\frac{1}{2}}}{2}$ from $\frac{u^{\frac{1}{2}}}{2}$ .

$u + 0 - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}}$

Step 7.3.4

Add $u$ and $0$ .

$u - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}} + u - \frac{\sqrt{u}}{2 u^{\frac{1}{2}}}$

Step 7.4

Combine the numerators over the common denominator.

$u + u + \frac{- \sqrt{u} - \sqrt{u}}{2 u^{\frac{1}{2}}}$

Step 7.5

Subtract $\sqrt{u}$ from $- \sqrt{u}$ .

$u + u + \frac{- 2 \sqrt{u}}{2 u^{\frac{1}{2}}}$

Step 7.6

Simplify each term.

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Step 7.6.1

Factor $2$ out of $- 2 \sqrt{u}$ .

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

Step 7.6.2

Cancel the common factors.

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Step 7.6.2.1

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

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

Step 7.6.2.2

Cancel the common factor.

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

Step 7.6.2.3

Rewrite the expression.

$u + u + \frac{- \sqrt{u}}{u^{\frac{1}{2}}}$

Step 7.6.3

Move the negative in front of the fraction.

$u + u - \frac{\sqrt{u}}{u^{\frac{1}{2}}}$

Step 7.7

Add $u$ and $u$ .

$2 u - \frac{\sqrt{u}}{u^{\frac{1}{2}}}$