Calculus Examples

$P (r) = \frac{5 (3 r + 1)}{r^{2} + r + 2}$

Step 1

Since $5$ is constant with respect to $r$ , the derivative of $\frac{5 (3 r + 1)}{r^{2} + r + 2}$ with respect to $r$ is $5 \frac{d}{d r} [\frac{3 r + 1}{r^{2} + r + 2}]$ .

$5 \frac{d}{d r} [\frac{3 r + 1}{r^{2} + r + 2}]$

Step 2

Differentiate using the Quotient Rule which states that $\frac{d}{d r} [\frac{f (r)}{g (r)}]$ is $\frac{g (r) \frac{d}{d r} [f (r)] - f (r) \frac{d}{d r} [g (r)]}{{g (r)}^{2}}$ where $f (r) = 3 r + 1$ and $g (r) = r^{2} + r + 2$ .

$5 \frac{(r^{2} + r + 2) \frac{d}{d r} [3 r + 1] - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3

Differentiate.

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Step 3.1

By the Sum Rule, the derivative of $3 r + 1$ with respect to $r$ is $\frac{d}{d r} [3 r] + \frac{d}{d r} [1]$ .

$5 \frac{(r^{2} + r + 2) (\frac{d}{d r} [3 r] + \frac{d}{d r} [1]) - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3.2

Since $3$ is constant with respect to $r$ , the derivative of $3 r$ with respect to $r$ is $3 \frac{d}{d r} [r]$ .

$5 \frac{(r^{2} + r + 2) (3 \frac{d}{d r} [r] + \frac{d}{d r} [1]) - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3.3

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

$5 \frac{(r^{2} + r + 2) (3 \cdot 1 + \frac{d}{d r} [1]) - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3.4

Multiply $3$ by $1$ .

$5 \frac{(r^{2} + r + 2) (3 + \frac{d}{d r} [1]) - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3.5

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

$5 \frac{(r^{2} + r + 2) (3 + 0) - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3.6

Simplify the expression.

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Step 3.6.1

Add $3$ and $0$ .

$5 \frac{(r^{2} + r + 2) \cdot 3 - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3.6.2

Move $3$ to the left of $r^{2} + r + 2$ .

$5 \frac{3 \cdot (r^{2} + r + 2) - (3 r + 1) \frac{d}{d r} [r^{2} + r + 2]}{{(r^{2} + r + 2)}^{2}}$

Step 3.7

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

$5 \frac{3 (r^{2} + r + 2) - (3 r + 1) (\frac{d}{d r} [r^{2}] + \frac{d}{d r} [r] + \frac{d}{d r} [2])}{{(r^{2} + r + 2)}^{2}}$

Step 3.8

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

$5 \frac{3 (r^{2} + r + 2) - (3 r + 1) (2 r + \frac{d}{d r} [r] + \frac{d}{d r} [2])}{{(r^{2} + r + 2)}^{2}}$

Step 3.9

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

$5 \frac{3 (r^{2} + r + 2) - (3 r + 1) (2 r + 1 + \frac{d}{d r} [2])}{{(r^{2} + r + 2)}^{2}}$

Step 3.10

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

$5 \frac{3 (r^{2} + r + 2) - (3 r + 1) (2 r + 1 + 0)}{{(r^{2} + r + 2)}^{2}}$

Step 3.11

Combine fractions.

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Step 3.11.1

Add $2 r + 1$ and $0$ .

$5 \frac{3 (r^{2} + r + 2) - (3 r + 1) (2 r + 1)}{{(r^{2} + r + 2)}^{2}}$

Step 3.11.2

Combine $5$ and $\frac{3 (r^{2} + r + 2) - (3 r + 1) (2 r + 1)}{{(r^{2} + r + 2)}^{2}}$ .

$\frac{5 (3 (r^{2} + r + 2) - (3 r + 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4

Simplify.

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Step 4.1

Apply the distributive property.

$\frac{5 (3 r^{2} + 3 r + 3 \cdot 2 - (3 r + 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.2

Apply the distributive property.

$\frac{5 (3 r^{2} + 3 r + 3 \cdot 2 + (- (3 r) - 1 \cdot 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.3

Apply the distributive property.

$\frac{5 (3 r^{2}) + 5 (3 r) + 5 (3 \cdot 2) + 5 ((- (3 r) - 1 \cdot 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4

Simplify the numerator.

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Step 4.4.1

Simplify each term.

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Step 4.4.1.1

Multiply $3$ by $5$ .

$\frac{15 r^{2} + 5 (3 r) + 5 (3 \cdot 2) + 5 ((- (3 r) - 1 \cdot 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.2

Multiply $3$ by $5$ .

$\frac{15 r^{2} + 15 r + 5 (3 \cdot 2) + 5 ((- (3 r) - 1 \cdot 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.3

Multiply $5 (3 \cdot 2)$ .

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Step 4.4.1.3.1

Multiply $3$ by $2$ .

$\frac{15 r^{2} + 15 r + 5 \cdot 6 + 5 ((- (3 r) - 1 \cdot 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.3.2

Multiply $5$ by $6$ .

$\frac{15 r^{2} + 15 r + 30 + 5 ((- (3 r) - 1 \cdot 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.4

Simplify each term.

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Step 4.4.1.4.1

Multiply $3$ by $- 1$ .

$\frac{15 r^{2} + 15 r + 30 + 5 ((- 3 r - 1 \cdot 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.4.2

Multiply $- 1$ by $1$ .

$\frac{15 r^{2} + 15 r + 30 + 5 ((- 3 r - 1) (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.5

Expand $(- 3 r - 1) (2 r + 1)$ using the FOIL Method.

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Step 4.4.1.5.1

Apply the distributive property.

$\frac{15 r^{2} + 15 r + 30 + 5 (- 3 r (2 r + 1) - 1 (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.5.2

Apply the distributive property.

$\frac{15 r^{2} + 15 r + 30 + 5 (- 3 r (2 r) - 3 r \cdot 1 - 1 (2 r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.5.3

Apply the distributive property.

$\frac{15 r^{2} + 15 r + 30 + 5 (- 3 r (2 r) - 3 r \cdot 1 - 1 (2 r) - 1 \cdot 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6

Simplify and combine like terms.

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Step 4.4.1.6.1

Simplify each term.

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Step 4.4.1.6.1.1

Rewrite using the commutative property of multiplication.

$\frac{15 r^{2} + 15 r + 30 + 5 (- 3 \cdot 2 r \cdot r - 3 r \cdot 1 - 1 (2 r) - 1 \cdot 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6.1.2

Multiply $r$ by $r$ by adding the exponents.

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Step 4.4.1.6.1.2.1

Move $r$ .

$\frac{15 r^{2} + 15 r + 30 + 5 (- 3 \cdot 2 (r \cdot r) - 3 r \cdot 1 - 1 (2 r) - 1 \cdot 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6.1.2.2

Multiply $r$ by $r$ .

$\frac{15 r^{2} + 15 r + 30 + 5 (- 3 \cdot 2 r^{2} - 3 r \cdot 1 - 1 (2 r) - 1 \cdot 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6.1.3

Multiply $- 3$ by $2$ .

$\frac{15 r^{2} + 15 r + 30 + 5 (- 6 r^{2} - 3 r \cdot 1 - 1 (2 r) - 1 \cdot 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6.1.4

Multiply $- 3$ by $1$ .

$\frac{15 r^{2} + 15 r + 30 + 5 (- 6 r^{2} - 3 r - 1 (2 r) - 1 \cdot 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6.1.5

Multiply $2$ by $- 1$ .

$\frac{15 r^{2} + 15 r + 30 + 5 (- 6 r^{2} - 3 r - 2 r - 1 \cdot 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6.1.6

Multiply $- 1$ by $1$ .

$\frac{15 r^{2} + 15 r + 30 + 5 (- 6 r^{2} - 3 r - 2 r - 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.6.2

Subtract $2 r$ from $- 3 r$ .

$\frac{15 r^{2} + 15 r + 30 + 5 (- 6 r^{2} - 5 r - 1)}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.7

Apply the distributive property.

$\frac{15 r^{2} + 15 r + 30 + 5 (- 6 r^{2}) + 5 (- 5 r) + 5 \cdot - 1}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.8

Simplify.

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Step 4.4.1.8.1

Multiply $- 6$ by $5$ .

$\frac{15 r^{2} + 15 r + 30 - 30 r^{2} + 5 (- 5 r) + 5 \cdot - 1}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.8.2

Multiply $- 5$ by $5$ .

$\frac{15 r^{2} + 15 r + 30 - 30 r^{2} - 25 r + 5 \cdot - 1}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.1.8.3

Multiply $5$ by $- 1$ .

$\frac{15 r^{2} + 15 r + 30 - 30 r^{2} - 25 r - 5}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.2

Subtract $30 r^{2}$ from $15 r^{2}$ .

$\frac{- 15 r^{2} + 15 r + 30 - 25 r - 5}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.3

Subtract $25 r$ from $15 r$ .

$\frac{- 15 r^{2} - 10 r + 30 - 5}{{(r^{2} + r + 2)}^{2}}$

Step 4.4.4

Subtract $5$ from $30$ .

$\frac{- 15 r^{2} - 10 r + 25}{{(r^{2} + r + 2)}^{2}}$

Step 4.5

Simplify the numerator.

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Step 4.5.1

Factor $5$ out of $- 15 r^{2} - 10 r + 25$ .

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Step 4.5.1.1

Factor $5$ out of $- 15 r^{2}$ .

$\frac{5 (- 3 r^{2}) - 10 r + 25}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.1.2

Factor $5$ out of $- 10 r$ .

$\frac{5 (- 3 r^{2}) + 5 (- 2 r) + 25}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.1.3

Factor $5$ out of $25$ .

$\frac{5 (- 3 r^{2}) + 5 (- 2 r) + 5 (5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.1.4

Factor $5$ out of $5 (- 3 r^{2}) + 5 (- 2 r)$ .

$\frac{5 (- 3 r^{2} - 2 r) + 5 (5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.1.5

Factor $5$ out of $5 (- 3 r^{2} - 2 r) + 5 (5)$ .

$\frac{5 (- 3 r^{2} - 2 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.2

Factor by grouping.

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Step 4.5.2.1

For a polynomial of the form $a x^{2} + b x + c$ , rewrite the middle term as a sum of two terms whose product is $a \cdot c = - 3 \cdot 5 = - 15$ and whose sum is $b = - 2$ .

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Step 4.5.2.1.1

Factor $- 2$ out of $- 2 r$ .

$\frac{5 (- 3 r^{2} - 2 (r) + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.2.1.2

Rewrite $- 2$ as $3$ plus $- 5$

$\frac{5 (- 3 r^{2} + (3 - 5) r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.2.1.3

Apply the distributive property.

$\frac{5 (- 3 r^{2} + 3 r - 5 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.2.2

Factor out the greatest common factor from each group.

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Step 4.5.2.2.1

Group the first two terms and the last two terms.

$\frac{5 ((- 3 r^{2} + 3 r) - 5 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.2.2.2

Factor out the greatest common factor (GCF) from each group.

$\frac{5 (3 r (- r + 1) + 5 (- r + 1))}{{(r^{2} + r + 2)}^{2}}$

Step 4.5.2.3

Factor the polynomial by factoring out the greatest common factor, $- r + 1$ .

$\frac{5 ((- r + 1) (3 r + 5))}{{(r^{2} + r + 2)}^{2}}$

$\frac{5 (- r + 1) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.6

Factor $- 1$ out of $- r$ .

$\frac{5 (- (r) + 1) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.7

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

$\frac{5 (- (r) - 1 (- 1)) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.8

Factor $- 1$ out of $- (r) - 1 (- 1)$ .

$\frac{5 (- (r - 1)) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.9

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

$\frac{5 (- 1 (r - 1)) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.10

Move the negative in front of the fraction.

$- \frac{(5 (r - 1)) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$

Step 4.11

Reorder factors in $- \frac{(5 (r - 1)) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$ .

$- \frac{5 (r - 1) (3 r + 5)}{{(r^{2} + r + 2)}^{2}}$