Calculus Examples

$e^{- x} (x^{2} + 2 x)$

Step 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 $f (x) = e^{- x}$ and $g (x) = x^{2} + 2 x$ .

$e^{- x} \frac{d}{d x} [x^{2} + 2 x] + (x^{2} + 2 x) \frac{d}{d x} [e^{- x}]$

Step 2

Differentiate.

Tap for more steps...

Step 2.1

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

$e^{- x} (\frac{d}{d x} [x^{2}] + \frac{d}{d x} [2 x]) + (x^{2} + 2 x) \frac{d}{d x} [e^{- x}]$

Step 2.2

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

$e^{- x} (2 x + \frac{d}{d x} [2 x]) + (x^{2} + 2 x) \frac{d}{d x} [e^{- x}]$

Step 2.3

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

$e^{- x} (2 x + 2 \frac{d}{d x} [x]) + (x^{2} + 2 x) \frac{d}{d x} [e^{- x}]$

Step 2.4

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

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

Step 2.5

Multiply $2$ by $1$ .

$e^{- x} (2 x + 2) + (x^{2} + 2 x) \frac{d}{d x} [e^{- x}]$

Step 3

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

Tap for more steps...

Step 3.1

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

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

Step 3.2

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

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

Step 3.3

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

$e^{- x} (2 x + 2) + (x^{2} + 2 x) (e^{- x} \frac{d}{d x} [- x])$

Step 4

Differentiate.

Tap for more steps...

Step 4.1

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

$e^{- x} (2 x + 2) + (x^{2} + 2 x) e^{- x} (- \frac{d}{d x} [x])$

Step 4.2

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

$e^{- x} (2 x + 2) + (x^{2} + 2 x) e^{- x} (- 1 \cdot 1)$

Step 4.3

Simplify the expression.

Tap for more steps...

Step 4.3.1

Multiply $- 1$ by $1$ .

$e^{- x} (2 x + 2) + (x^{2} + 2 x) e^{- x} \cdot - 1$

Step 4.3.2

Move $- 1$ to the left of $(x^{2} + 2 x) e^{- x}$ .

$e^{- x} (2 x + 2) - 1 \cdot ((x^{2} + 2 x) e^{- x})$

Step 4.3.3

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

$e^{- x} (2 x + 2) - (x^{2} + 2 x) e^{- x}$

Step 5

Simplify.

Tap for more steps...

Step 5.1

Apply the distributive property.

$e^{- x} (2 x) + e^{- x} \cdot 2 - (x^{2} + 2 x) e^{- x}$

Step 5.2

Apply the distributive property.

$e^{- x} (2 x) + e^{- x} \cdot 2 + (- x^{2} - (2 x)) e^{- x}$

Step 5.3

Apply the distributive property.

$e^{- x} (2 x) + e^{- x} \cdot 2 - x^{2} e^{- x} - (2 x) e^{- x}$

Step 5.4

Combine terms.

Tap for more steps...

Step 5.4.1

Move $2$ to the left of $e^{- x}$ .

$e^{- x} (2 x) + 2 \cdot e^{- x} - x^{2} e^{- x} - (2 x) e^{- x}$

Step 5.4.2

Multiply $2$ by $- 1$ .

$e^{- x} (2 x) + 2 e^{- x} - x^{2} e^{- x} - 2 x e^{- x}$

Step 5.4.3

Subtract $2 x e^{- x}$ from $e^{- x} (2 x)$ .

Tap for more steps...

Step 5.4.3.1

Move $e^{- x}$ .

$2 e^{- x} - x^{2} e^{- x} + 2 x e^{- x} - 2 x e^{- x}$

Step 5.4.3.2

Subtract $2 x e^{- x}$ from $2 x e^{- x}$ .

$2 e^{- x} - x^{2} e^{- x} + 0$

Step 5.4.4

Add $2 e^{- x} - x^{2} e^{- x}$ and $0$ .

$2 e^{- x} - x^{2} e^{- x}$

Step 5.5

Reorder terms.

$- e^{- x} x^{2} + 2 e^{- x}$

Step 5.6

Reorder factors in $- e^{- x} x^{2} + 2 e^{- x}$ .

$- x^{2} e^{- x} + 2 e^{- x}$