Calculus Examples

$p = \frac{500}{12 + 5 e^{- 0.5 t}}$

Step 1

Differentiate both sides of the equation.

$\frac{d}{d t} (p) = \frac{d}{d t} (\frac{500}{12 + 5 e^{- 0.5 t}})$

Step 2

The derivative of $p$ with respect to $t$ is $p'$ .

$p'$

Step 3

Differentiate the right side of the equation.

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Step 3.1

Differentiate using the Constant Multiple Rule.

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Step 3.1.1

Since $500$ is constant with respect to $t$ , the derivative of $\frac{500}{12 + 5 e^{- 0.5 t}}$ with respect to $t$ is $500 \frac{d}{d t} [\frac{1}{12 + 5 e^{- 0.5 t}}]$ .

$500 \frac{d}{d t} [\frac{1}{12 + 5 e^{- 0.5 t}}]$

Step 3.1.2

Rewrite $\frac{1}{12 + 5 e^{- 0.5 t}}$ as ${(12 + 5 e^{- 0.5 t})}^{- 1}$ .

$500 \frac{d}{d t} [{(12 + 5 e^{- 0.5 t})}^{- 1}]$

Step 3.2

Differentiate using the chain rule, which states that $\frac{d}{d t} [f (g (t))]$ is $f' (g (t)) g' (t)$ where $f (t) = t^{- 1}$ and $g (t) = 12 + 5 e^{- 0.5 t}$ .

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Step 3.2.1

To apply the Chain Rule, set $u_{1}$ as $12 + 5 e^{- 0.5 t}$ .

$500 (\frac{d}{d u_{1}} [{u_{1}}^{- 1}] \frac{d}{d t} [12 + 5 e^{- 0.5 t}])$

Step 3.2.2

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

$500 (- {u_{1}}^{- 2} \frac{d}{d t} [12 + 5 e^{- 0.5 t}])$

Step 3.2.3

Replace all occurrences of $u_{1}$ with $12 + 5 e^{- 0.5 t}$ .

$500 (- {(12 + 5 e^{- 0.5 t})}^{- 2} \frac{d}{d t} [12 + 5 e^{- 0.5 t}])$

Step 3.3

Differentiate.

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Step 3.3.1

Multiply $- 1$ by $500$ .

$- 500 ({(12 + 5 e^{- 0.5 t})}^{- 2} \frac{d}{d t} [12 + 5 e^{- 0.5 t}])$

Step 3.3.2

By the Sum Rule, the derivative of $12 + 5 e^{- 0.5 t}$ with respect to $t$ is $\frac{d}{d t} [12] + \frac{d}{d t} [5 e^{- 0.5 t}]$ .

$- 500 {(12 + 5 e^{- 0.5 t})}^{- 2} (\frac{d}{d t} [12] + \frac{d}{d t} [5 e^{- 0.5 t}])$

Step 3.3.3

Since $12$ is constant with respect to $t$ , the derivative of $12$ with respect to $t$ is $0$ .

$- 500 {(12 + 5 e^{- 0.5 t})}^{- 2} (0 + \frac{d}{d t} [5 e^{- 0.5 t}])$

Step 3.3.4

Add $0$ and $\frac{d}{d t} [5 e^{- 0.5 t}]$ .

$- 500 {(12 + 5 e^{- 0.5 t})}^{- 2} \frac{d}{d t} [5 e^{- 0.5 t}]$

Step 3.3.5

Since $5$ is constant with respect to $t$ , the derivative of $5 e^{- 0.5 t}$ with respect to $t$ is $5 \frac{d}{d t} [e^{- 0.5 t}]$ .

$- 500 {(12 + 5 e^{- 0.5 t})}^{- 2} (5 \frac{d}{d t} [e^{- 0.5 t}])$

Step 3.3.6

Multiply $5$ by $- 500$ .

$- 2500 {(12 + 5 e^{- 0.5 t})}^{- 2} \frac{d}{d t} [e^{- 0.5 t}]$

Step 3.4

Differentiate using the chain rule, which states that $\frac{d}{d t} [f (g (t))]$ is $f' (g (t)) g' (t)$ where $f (t) = e^{t}$ and $g (t) = - 0.5 t$ .

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Step 3.4.1

To apply the Chain Rule, set $u_{2}$ as $- 0.5 t$ .

$- 2500 {(12 + 5 e^{- 0.5 t})}^{- 2} (\frac{d}{d u_{2}} [e^{u_{2}}] \frac{d}{d t} [- 0.5 t])$

Step 3.4.2

Differentiate using the Exponential Rule which states that $\frac{d}{d u_{2}} [a^{u_{2}}]$ is $a^{u_{2}} \ln (a)$ where $a$ = $e$ .

$- 2500 {(12 + 5 e^{- 0.5 t})}^{- 2} (e^{u_{2}} \frac{d}{d t} [- 0.5 t])$

Step 3.4.3

Replace all occurrences of $u_{2}$ with $- 0.5 t$ .

$- 2500 {(12 + 5 e^{- 0.5 t})}^{- 2} (e^{- 0.5 t} \frac{d}{d t} [- 0.5 t])$

Step 3.5

Differentiate.

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Step 3.5.1

Since $- 0.5$ is constant with respect to $t$ , the derivative of $- 0.5 t$ with respect to $t$ is $- 0.5 \frac{d}{d t} [t]$ .

$- 2500 {(12 + 5 e^{- 0.5 t})}^{- 2} (e^{- 0.5 t} (- 0.5 \frac{d}{d t} [t]))$

Step 3.5.2

Multiply $- 0.5$ by $- 2500$ .

$1250 {(12 + 5 e^{- 0.5 t})}^{- 2} (e^{- 0.5 t} (\frac{d}{d t} [t]))$

Step 3.5.3

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

$1250 {(12 + 5 e^{- 0.5 t})}^{- 2} (e^{- 0.5 t} \cdot 1)$

Step 3.5.4

Multiply $e^{- 0.5 t}$ by $1$ .

$1250 {(12 + 5 e^{- 0.5 t})}^{- 2} e^{- 0.5 t}$

Step 3.6

Simplify.

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Step 3.6.1

Reorder the factors of $1250 {(12 + 5 e^{- 0.5 t})}^{- 2} e^{- 0.5 t}$ .

$1250 e^{- 0.5 t} {(12 + 5 e^{- 0.5 t})}^{- 2}$

Step 3.6.2

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

$1250 e^{- 0.5 t} \frac{1}{{(12 + 5 e^{- 0.5 t})}^{2}}$

Step 3.6.3

Multiply $1250 e^{- 0.5 t} \frac{1}{{(12 + 5 e^{- 0.5 t})}^{2}}$ .

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Step 3.6.3.1

Combine $\frac{1}{{(12 + 5 e^{- 0.5 t})}^{2}}$ and $1250$ .

$\frac{1250}{{(12 + 5 e^{- 0.5 t})}^{2}} e^{- 0.5 t}$

Step 3.6.3.2

Combine $\frac{1250}{{(12 + 5 e^{- 0.5 t})}^{2}}$ and $e^{- 0.5 t}$ .

$\frac{1250 e^{- 0.5 t}}{{(12 + 5 e^{- 0.5 t})}^{2}}$

Step 4

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

$p' = \frac{1250 e^{- 0.5 t}}{{(12 + 5 e^{- 0.5 t})}^{2}}$

Step 5

Replace $p'$ with $\frac{d p}{d t}$ .

$\frac{d p}{d t} = \frac{1250 e^{- 0.5 t}}{{(12 + 5 e^{- 0.5 t})}^{2}}$