Calculus Examples

$7 e^{- 0.2 t} (1 - 0.2 t)$

Step 1

Since $7$ is constant with respect to $t$ , the derivative of $7 e^{- 0.2 t} (1 - 0.2 t)$ with respect to $t$ is $7 \frac{d}{d t} [e^{- 0.2 t} (1 - 0.2 t)]$ .

$7 \frac{d}{d t} [e^{- 0.2 t} (1 - 0.2 t)]$

Step 2

Differentiate using the Product Rule which states that $\frac{d}{d t} [f (t) g (t)]$ is $f (t) \frac{d}{d t} [g (t)] + g (t) \frac{d}{d t} [f (t)]$ where $f (t) = e^{- 0.2 t}$ and $g (t) = 1 - 0.2 t$ .

$7 (e^{- 0.2 t} \frac{d}{d t} [1 - 0.2 t] + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 3

Differentiate.

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Step 3.1

By the Sum Rule, the derivative of $1 - 0.2 t$ with respect to $t$ is $\frac{d}{d t} [1] + \frac{d}{d t} [- 0.2 t]$ .

$7 (e^{- 0.2 t} (\frac{d}{d t} [1] + \frac{d}{d t} [- 0.2 t]) + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 3.2

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

$7 (e^{- 0.2 t} (0 + \frac{d}{d t} [- 0.2 t]) + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 3.3

Add $0$ and $\frac{d}{d t} [- 0.2 t]$ .

$7 (e^{- 0.2 t} \frac{d}{d t} [- 0.2 t] + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 3.4

Since $- 0.2$ is constant with respect to $t$ , the derivative of $- 0.2 t$ with respect to $t$ is $- 0.2 \frac{d}{d t} [t]$ .

$7 (e^{- 0.2 t} (- 0.2 \frac{d}{d t} [t]) + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 3.5

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

$7 (e^{- 0.2 t} (- 0.2 \cdot 1) + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 3.6

Simplify the expression.

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Step 3.6.1

Multiply $- 0.2$ by $1$ .

$7 (e^{- 0.2 t} \cdot - 0.2 + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 3.6.2

Move $- 0.2$ to the left of $e^{- 0.2 t}$ .

$7 (- 0.2 \cdot e^{- 0.2 t} + (1 - 0.2 t) \frac{d}{d t} [e^{- 0.2 t}])$

Step 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 $g (t) = - 0.2 t$ .

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Step 4.1

To apply the Chain Rule, set $u$ as $- 0.2 t$ .

$7 (- 0.2 e^{- 0.2 t} + (1 - 0.2 t) (\frac{d}{d u} [e^{u}] \frac{d}{d t} [- 0.2 t]))$

Step 4.2

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

$7 (- 0.2 e^{- 0.2 t} + (1 - 0.2 t) (e^{u} \frac{d}{d t} [- 0.2 t]))$

Step 4.3

Replace all occurrences of $u$ with $- 0.2 t$ .

$7 (- 0.2 e^{- 0.2 t} + (1 - 0.2 t) (e^{- 0.2 t} \frac{d}{d t} [- 0.2 t]))$

Step 5

Differentiate.

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Step 5.1

Since $- 0.2$ is constant with respect to $t$ , the derivative of $- 0.2 t$ with respect to $t$ is $- 0.2 \frac{d}{d t} [t]$ .

$7 (- 0.2 e^{- 0.2 t} + (1 - 0.2 t) e^{- 0.2 t} (- 0.2 \frac{d}{d t} [t]))$

Step 5.2

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

$7 (- 0.2 e^{- 0.2 t} + (1 - 0.2 t) e^{- 0.2 t} (- 0.2 \cdot 1))$

Step 5.3

Simplify the expression.

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Step 5.3.1

Multiply $- 0.2$ by $1$ .

$7 (- 0.2 e^{- 0.2 t} + (1 - 0.2 t) e^{- 0.2 t} \cdot - 0.2)$

Step 5.3.2

Move $- 0.2$ to the left of $(1 - 0.2 t) e^{- 0.2 t}$ .

$7 (- 0.2 e^{- 0.2 t} - 0.2 \cdot ((1 - 0.2 t) e^{- 0.2 t}))$

Step 6

Simplify.

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Step 6.1

Apply the distributive property.

$7 (- 0.2 e^{- 0.2 t} + (- 0.2 \cdot 1 - 0.2 (- 0.2 t)) e^{- 0.2 t})$

Step 6.2

Apply the distributive property.

$7 (- 0.2 e^{- 0.2 t} - 0.2 \cdot 1 e^{- 0.2 t} - 0.2 (- 0.2 t) e^{- 0.2 t})$

Step 6.3

Apply the distributive property.

$7 (- 0.2 e^{- 0.2 t}) + 7 (- 0.2 \cdot 1 e^{- 0.2 t}) + 7 (- 0.2 (- 0.2 t) e^{- 0.2 t})$

Step 6.4

Combine terms.

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Step 6.4.1

Multiply $- 0.2$ by $7$ .

$- 1.4 e^{- 0.2 t} + 7 (- 0.2 \cdot 1 e^{- 0.2 t}) + 7 (- 0.2 (- 0.2 t) e^{- 0.2 t})$

Step 6.4.2

Multiply $- 0.2$ by $1$ .

$- 1.4 e^{- 0.2 t} + 7 (- 0.2 e^{- 0.2 t}) + 7 (- 0.2 (- 0.2 t) e^{- 0.2 t})$

Step 6.4.3

Multiply $- 0.2$ by $7$ .

$- 1.4 e^{- 0.2 t} - 1.4 e^{- 0.2 t} + 7 (- 0.2 (- 0.2 t) e^{- 0.2 t})$

Step 6.4.4

Multiply $- 0.2$ by $- 0.2$ .

$- 1.4 e^{- 0.2 t} - 1.4 e^{- 0.2 t} + 7 (0.04 t e^{- 0.2 t})$

Step 6.4.5

Multiply $0.04$ by $7$ .

$- 1.4 e^{- 0.2 t} - 1.4 e^{- 0.2 t} + 0.28 (t e^{- 0.2 t})$

Step 6.4.6

Subtract $1.4 e^{- 0.2 t}$ from $- 1.4 e^{- 0.2 t}$ .

$- 2.8 e^{- 0.2 t} + 0.28 t e^{- 0.2 t}$

Step 6.5

Reorder terms.

$0.28 e^{- 0.2 t} t - 2.8 e^{- 0.2 t}$

Step 6.6

Reorder factors in $0.28 e^{- 0.2 t} t - 2.8 e^{- 0.2 t}$ .

$0.28 t e^{- 0.2 t} - 2.8 e^{- 0.2 t}$