Chapter 8: Problem 18
The integrals in Exercises \(1-44\) are in no particular order. Evaluate each integral using any algebraic method or trigonometric identity you think is appropriate. When necessary, use a substitution to reduce it to a standard form. $$ \int \frac{2^{\sqrt{y}} d y}{2 \sqrt{y}} $$
Short Answer
Expert verified
\( \frac{2^{\sqrt{y}}}{\ln(2)} + C \)
Step by step solution
01
Simplify the Integral
First, observe that the integral can be simplified by noticing that the expression under the integral consists of two parts: the function inside the numerator and the function in the denominator. The integral can be rewritten as \( \int \frac{2^{\sqrt{y}}}{2 \sqrt{y}} \, dy = \int \frac{1}{2} 2^{\sqrt{y}} \frac{1}{\sqrt{y}} \, dy \). This form suggests the use of substitution.
02
Choose a Substitution
We choose a substitution to simplify the integral. Let \( u = \sqrt{y} \). Then, \( y = u^2 \) and \( dy = 2u \, du \). Substitute into the integral to get \[ \int \frac{2^{u} \, 2u \, du}{2u} = \int 2^{u} \, du. \]
03
Evaluate the Integral
Now, our integral has been transformed into \( \int 2^{u} \, du \). We apply the integration formula for exponential functions: \( \int a^{u} \, du = \frac{a^{u}}{\ln(a)} + C \). Here, \( a = 2 \), thus \( \int 2^{u} \, du = \frac{2^{u}}{\ln(2)} + C \).
04
Substitute Back
The final step is to substitute back the original variable \( y \) for \( u \). Recall that \( u = \sqrt{y} \). So, the integral becomes \[ \frac{2^{\sqrt{y}}}{\ln(2)} + C \].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution Method
The substitution method is a powerful technique in integration. It's especially useful when an integral seems difficult to solve in its original form. This method involves replacing a part of the integral with a new variable, thereby simplifying the problem. Here's a simple step-by-step for the substitution method:
- Choose a substitution: Identify a part of the integral that can be replaced with a new variable, say \( u \). This often simplifies the expression. For example, if you have \( y \) in the integral \( \int \frac{2^{\sqrt{y}} d y}{2 \sqrt{y}} \), you might set \( u = \sqrt{y} \).
- Find \( dy \): Express \( dy \) in terms of \( du \). In our substitution, \( dy = 2u \, du \).
- Substitute: Replace all occurrences of the original variable in the integral with your new variable and expressions related to it. Your goal is to transform the integral into a simpler form, as in \( \int 2^{u} \, du \).
- Integrate: Perform the integration on the simplified integral.
- Substitute back: Once integrated, replace the substitution variable back with the original term to return to the variable the problem started with.
Exponential Functions
Exponential functions are a staple in integration problems and mathematics in general. These functions take the form \( a^x \), where \( a \) is a constant base and \( x \) is the exponent. In our case, we dealt with an exponential function \( 2^{\sqrt{y}} \). When integrating exponential functions like this, there's a general principle:
- Integration formula: The rule \( \int a^u \, du = \frac{a^u}{\ln(a)} + C \), states that when integrating \( a^u \), divide by the natural log of the base \( a \).
- Handling exponential growth: Exponential functions grow rapidly. When integrated, they model real-world processes like population growth, radioactive decay, and interest calculations effectively.
Definite and Indefinite Integrals
The integration process can lead to either a definite or an indefinite integral, each serving a different purpose in mathematics.
- Indefinite Integrals: This is what we calculated in the solution. An indefinite integral represents a family of functions and includes a constant \( C \). For example, our result \( \frac{2^{\sqrt{y}}}{\ln(2)} + C \) is an indefinite integral.
- Definite Integrals: Unlike indefinite integrals, definite integrals have limits of integration. They compute the exact area under a curve between two bounds. They give a specific numerical value rather than a function.
- When to use which: Use indefinite integrals when seeking a general solution or family of solutions. Opt for definite integrals when solving for an exact value or area.