Problem

Find dy/dx y=3^( square root of x)

The question is asking for the derivative of the function y with respect to x, where y is defined as 3 raised to the power of the square root of x. Essentially, it requires you to perform differentiation, which is a calculus technique used to find the rate at which one quantity changes with respect to another. The question is about applying the chain rule of differentiation, which involves computing the derivative of composite functions.

$y = 3^{\sqrt{x}}$

Answer

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Solution:

Step 1:

Rewrite the given function using the property that $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$. Thus, we have $y = 3^{x^{\frac{1}{2}}}$.

Step 2:

Take the derivative of both sides with respect to $x$: $\frac{d}{dx}y = \frac{d}{dx}3^{x^{\frac{1}{2}}}$.

Step 3:

The derivative of $y$ with respect to $x$ is denoted by $\frac{dy}{dx}$.

Step 4:

Proceed to differentiate the right-hand side of the equation.

Step 4.1:

Apply the chain rule for differentiation: $\frac{d}{dx}[f(g(x))] = f'(g(x)) \cdot g'(x)$, where $f(x) = 3^{x}$ and $g(x) = x^{\frac{1}{2}}$.

Step 4.1.1:

Let $u = x^{\frac{1}{2}}$. Then differentiate $3^{u}$ with respect to $u$ and $x^{\frac{1}{2}}$ with respect to $x$: $\frac{d}{du}3^{u} \cdot \frac{d}{dx}x^{\frac{1}{2}}$.

Step 4.1.2:

Use the exponential rule for differentiation: $\frac{d}{du}a^{u} = a^{u} \ln(a)$, where $a = 3$. This gives us $3^{u} \ln(3) \cdot \frac{d}{dx}x^{\frac{1}{2}}$.

Step 4.1.3:

Substitute back $u = x^{\frac{1}{2}}$ to get $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{d}{dx}x^{\frac{1}{2}}$.

Step 4.2:

Apply the power rule for differentiation: $\frac{d}{dx}x^{n} = nx^{n-1}$, where $n = \frac{1}{2}$. This results in $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{1}{2} x^{\frac{1}{2} - 1}$.

Step 4.3:

Express $-1$ as a fraction with a common denominator by multiplying by $\frac{2}{2}$: $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{1}{2} x^{\frac{1}{2} - 1 \cdot \frac{2}{2}}$.

Step 4.4:

Combine the terms in the exponent: $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{1}{2} x^{\frac{1}{2} + \frac{-2}{2}}$.

Step 4.5:

Add the numerators over the common denominator: $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{1}{2} x^{\frac{1 - 2}{2}}$.

Step 4.6:

Simplify the exponent by performing the subtraction in the numerator: $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{1}{2} x^{\frac{-1}{2}}$.

Step 4.7:

Rewrite the expression by moving the negative exponent to the denominator: $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{1}{2} x^{-\frac{1}{2}}$.

Step 4.8:

Combine the fraction and the exponent: $3^{x^{\frac{1}{2}}} \ln(3) \cdot \frac{x^{-\frac{1}{2}}}{2}$.

Step 4.9:

Multiply the terms together: $\frac{x^{-\frac{1}{2}} \cdot 3^{x^{\frac{1}{2}}}}{2} \ln(3)$.

Step 4.10:

Combine the fraction and the natural logarithm: $\frac{x^{-\frac{1}{2}} \cdot 3^{x^{\frac{1}{2}}} \ln(3)}{2}$.

Step 4.11:

Apply the negative exponent rule $b^{-n} = \frac{1}{b^{n}}$ to move $x^{-\frac{1}{2}}$ to the denominator: $\frac{3^{x^{\frac{1}{2}}} \ln(3)}{2x^{\frac{1}{2}}}$.

Step 5:

Express the derivative $\frac{dy}{dx}$ as the result of the differentiation: $\frac{dy}{dx} = \frac{3^{x^{\frac{1}{2}}} \ln(3)}{2x^{\frac{1}{2}}}$.

Step 6:

Substitute $\frac{dy}{dx}$ for $y$ in the final expression: $\frac{dy}{dx} = \frac{3^{x^{\frac{1}{2}}} \ln(3)}{2x^{\frac{1}{2}}}$.

Knowledge Notes:

  1. Exponentiation of a Root: The expression $\sqrt[n]{a^{x}}$ can be rewritten as $a^{\frac{x}{n}}$.

  2. Chain Rule: The chain rule is a fundamental property in calculus used to differentiate compositions of functions. It states that $\frac{d}{dx}[f(g(x))] = f'(g(x)) \cdot g'(x)$.

  3. Exponential Rule: When differentiating an exponential function $a^{u}$, where $a$ is a constant and $u$ is a function of $x$, the derivative is $a^{u} \ln(a) \cdot \frac{du}{dx}$.

  4. Power Rule: The power rule for differentiation states that if $f(x) = x^{n}$, then $f'(x) = nx^{n-1}$.

  5. Negative Exponent Rule: For any nonzero number $b$ and integer $n$, $b^{-n} = \frac{1}{b^{n}}$.

  6. Natural Logarithm (ln): The natural logarithm of a number is its logarithm to the base of the mathematical constant $e$, where $e$ is an irrational and transcendental number approximately equal to 2.71828.

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