Precalculus Examples

$g (x) = 3 x^{2} e^{2 x}$

Step 1

Since $3$ is constant with respect to $x$ , the derivative of $3 x^{2} e^{2 x}$ with respect to $x$ is $3 \frac{d}{d x} [x^{2} e^{2 x}]$ .

$3 \frac{d}{d x} [x^{2} e^{2 x}]$

Step 2

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

$3 (x^{2} \frac{d}{d x} [e^{2 x}] + e^{2 x} \frac{d}{d x} [x^{2}])$

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 $g (x) = 2 x$ .

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Step 3.1

To apply the Chain Rule, set $u$ as $2 x$ .

$3 (x^{2} (\frac{d}{d u} [e^{u}] \frac{d}{d x} [2 x]) + e^{2 x} \frac{d}{d x} [x^{2}])$

Step 3.2

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

$3 (x^{2} (e^{u} \frac{d}{d x} [2 x]) + e^{2 x} \frac{d}{d x} [x^{2}])$

Step 3.3

Replace all occurrences of $u$ with $2 x$ .

$3 (x^{2} (e^{2 x} \frac{d}{d x} [2 x]) + e^{2 x} \frac{d}{d x} [x^{2}])$

Step 4

Differentiate.

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Step 4.1

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

$3 (x^{2} (e^{2 x} (2 \frac{d}{d x} [x])) + e^{2 x} \frac{d}{d x} [x^{2}])$

Step 4.2

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

$3 (x^{2} (e^{2 x} (2 \cdot 1)) + e^{2 x} \frac{d}{d x} [x^{2}])$

Step 4.3

Simplify the expression.

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Step 4.3.1

Multiply $2$ by $1$ .

$3 (x^{2} (e^{2 x} \cdot 2) + e^{2 x} \frac{d}{d x} [x^{2}])$

Step 4.3.2

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

$3 (x^{2} (2 \cdot e^{2 x}) + e^{2 x} \frac{d}{d x} [x^{2}])$

Step 4.4

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

$3 (x^{2} (2 e^{2 x}) + e^{2 x} (2 x))$

Step 5

Simplify.

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Step 5.1

Apply the distributive property.

$3 (x^{2} (2 e^{2 x})) + 3 (e^{2 x} (2 x))$

Step 5.2

Combine terms.

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Step 5.2.1

Multiply $2$ by $3$ .

$6 (x^{2} (e^{2 x})) + 3 (e^{2 x} (2 x))$

Step 5.2.2

Multiply $2$ by $3$ .

$6 x^{2} e^{2 x} + 6 e^{2 x} x$

Step 5.3

Reorder terms.

$6 e^{2 x} x^{2} + 6 e^{2 x} x$

Step 5.4

Reorder factors in $6 e^{2 x} x^{2} + 6 e^{2 x} x$ .

$6 x^{2} e^{2 x} + 6 x e^{2 x}$