Problem

Integrate Using u-Substitution integral of (sin( square root of x))/( square root of x) with respect to x

The question asks for the evaluation of an integral using the u-substitution method. The integral to be evaluated is the integral of the function (sin(√x))/(√x) with respect to x. The integral involves a trigonometric function (sine) and a square root function in its integrand.

The u-substitution method is a common technique used in calculus to simplify integration by substituting a part of the integrand with a new variable, often denoted as 'u'. This often simplifies the integral into a form that is easier to integrate. Once the integration is done in terms of 'u', the variable is then substituted back into terms of 'x' to obtain the final result. The question expects the explanation or execution of this process for the given integrand.

$\int \frac{sin \left(\right. \sqrt{x} \left.\right)}{\sqrt{x}} d x$

Answer

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Solution:

Step:1

Implement exponent rules.

Step:1.1

Express $\sqrt{x}$ as $x^{\frac{1}{2}}$ using the rule $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$.
$\int \frac{\sin(x^{\frac{1}{2}})}{\sqrt{x}} dx$

Step:1.2

Again, express $\sqrt{x}$ as $x^{\frac{1}{2}}$.
$\int \frac{\sin(x^{\frac{1}{2}})}{x^{\frac{1}{2}}} dx$

Step:1.3

Transform $x^{\frac{1}{2}}$ in the denominator to the numerator by using the negative exponent.
$\int \sin(x^{\frac{1}{2}}) (x^{\frac{1}{2}})^{-1} dx$

Step:1.4

Apply exponent multiplication in $(x^{\frac{1}{2}})^{-1}$.

Step:1.4.1

Utilize the exponent multiplication rule, $(a^{m})^{n} = a^{mn}$.
$\int \sin(x^{\frac{1}{2}}) x^{\frac{1}{2} \cdot -1} dx$

Step:1.4.2

Combine the exponents $\frac{1}{2}$ and $-1$.
$\int \sin(x^{\frac{1}{2}}) x^{-\frac{1}{2}} dx$

Step:1.4.3

Place the negative sign in front of the fraction.
$\int \sin(x^{\frac{1}{2}}) x^{-\frac{1}{2}} dx$

Step:2

Set $u = x^{\frac{1}{2}}$. Then $du = \frac{1}{2x^{\frac{1}{2}}} dx$, and $dx = 2x^{\frac{1}{2}} du$. Substitute $u$ and $du$ into the integral.

Step:2.1

Define $u = x^{\frac{1}{2}}$ and calculate $\frac{du}{dx}$.

Step:2.1.1

Differentiate $x^{\frac{1}{2}}$.
$\frac{d}{dx} [x^{\frac{1}{2}}]$

Step:2.1.2

Apply the Power Rule, $\frac{d}{dx} [x^{n}] = nx^{n - 1}$, where $n = \frac{1}{2}$.
$\frac{1}{2} x^{\frac{1}{2} - 1}$

Step:2.1.3

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

Step:2.1.4

Combine $-1$ and $\frac{2}{2}$.
$\frac{1}{2} x^{\frac{1}{2} - \frac{2}{2}}$

Step:2.1.5

Add the numerators over the common denominator.
$\frac{1}{2} x^{\frac{1 - 2}{2}}$

Step:2.1.6

Simplify the numerator.

Step:2.1.6.1

Multiply $-1$ by $2$.
$\frac{1}{2} x^{\frac{-1}{2}}$

Step:2.1.6.2

Subtract $2$ from $1$.
$\frac{1}{2} x^{-\frac{1}{2}}$

Step:2.1.7

Move the negative in front of the fraction.
$\frac{1}{2} x^{-\frac{1}{2}}$

Step:2.1.8

Simplify further.

Step:2.1.8.1

Apply the negative exponent rule $b^{-n} = \frac{1}{b^{n}}$.
$\frac{1}{2} \cdot \frac{1}{x^{\frac{1}{2}}}$

Step:2.1.8.2

Multiply $\frac{1}{2}$ by $\frac{1}{x^{\frac{1}{2}}}$.
$\frac{1}{2x^{\frac{1}{2}}}$

Step:2.2

Reformulate the integral with $u$ and $du$.
$\int 2 \sin(u) du$

Step:3

Extract the constant $2$ from the integral as it is not dependent on $u$.
$2 \int \sin(u) du$

Step:4

Integrate $\sin(u)$ with respect to $u$ to get $- \cos(u)$.
$2 (-\cos(u) + C)$

Step:5

Simplify the expression.

Step:5.1

Simplify the result.
$2 (-\cos(u)) + C$

Step:5.2

Multiply $-1$ by $2$.
$-2 \cos(u) + C$

Step:6

Substitute $u$ back with $x^{\frac{1}{2}}$.
$-2 \cos(x^{\frac{1}{2}}) + C$

Knowledge Notes:

  1. Exponent Rules: These include the power of a power rule, product of powers rule, and negative exponent rule, which are fundamental in simplifying expressions with exponents.

  2. u-Substitution: A technique used in integration to simplify the integral by substituting part of the integrand with a new variable, $u$. This often simplifies the integral into a more recognizable form.

  3. Power Rule for Differentiation: A basic rule of differentiation that states if $f(x) = x^n$, then $f'(x) = nx^{n-1}$.

  4. Integration of Trigonometric Functions: The integral of $\sin(x)$ is $-\cos(x)$, and this is a basic integral that is often memorized.

  5. Negative Exponent Rule: States that $a^{-n} = \frac{1}{a^n}$, which is used to transform expressions with negative exponents into fractions.

  6. Constant Multiple Rule in Integration: Allows a constant to be moved outside of an integral, which can simplify the integration process.

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