Chapter 8: Problem 18
Evaluate each integral using any algebraic method or trigonometric identity you think is appropriate, and then use a substitution to reduce it to a standard form. $$\int \frac{2^{\sqrt{y}} d y}{2 \sqrt{y}}$$
Short Answer
Expert verified
The integral evaluates to \( \frac{2^{\sqrt{y}}}{\ln 2} + C \).
Step by step solution
01
Identify the Integral Form
The given integral is \( \int \frac{2^{\sqrt{y}} \, dy}{2 \sqrt{y}} \). Notice the presence of \( \sqrt{y} \) in the denominator and as an exponent. This suggests using a substitution could simplify the integral.
02
Choose a Substitution
Let \( u = \sqrt{y} \). Then, \( y = u^2 \) and \( dy = 2u \, du \). Substitute these into the integral.
03
Substitute and Simplify
Substituting \( y = u^2 \) and \( dy = 2u \, du \) into the integral gives:\[\int \frac{2^{u} \, (2u \, du)}{2u} = \int 2^{u} \, du\]The terms \( 2u \) in the numerator and denominator cancel out.
04
Integrate the Simplified Integral
The integral \( \int 2^u \, du \) is a basic exponential integral. The antiderivative of \( 2^u \) with respect to \( u \) is \( \frac{2^u}{\ln 2} + C \), where \( C \) is an integration constant.
05
Substitute Back to Original Variable
Recall \( u = \sqrt{y} \). Substitute \( u \) back to get:\[\frac{2^{\sqrt{y}}}{\ln 2} + C\]This is the result in terms of the original variable \( y \).
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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 integration technique often used to simplify complex expressions. When you encounter an integral, identifying a substitution can transform a difficult integral into an easier, more recognizable form. In the exercise above, we dealt with integrating an expression with a square root and exponential term.
- The first step is to choose a substitution that simplifies the integral. In this context, substituting helps manage complex square roots and exponential expressions. By setting a new variable, typically denoted as \( u \), you replace a difficult part of the integral, making it easier to work with.
- For example, let \( u = \sqrt{y} \), transforming all parts involving \( y \) into expressions involving \( u \). This substitution turns the original integral into a more straightforward exponential integral, allowing for easier integration techniques to be applied.
Exponential Integrals
Exponential integrals are integrals involving exponential functions, which often have specific forms and rules. They're a staple in calculus because exponential functions like \( a^x \), where \( a \) is a constant, can model various natural phenomena.
- To integrate \( a^u \), where \( a \) is a constant, the antiderivative is \( \frac{a^u}{\ln a} + C \). This formula is crucial when dealing with exponential integrals, as it provides a straightforward method to find the indefinite integral.
- In the given exercise, after employing the substitution method, the remaining integral was \( \int 2^u \, du \). Using the exponential integral rule, the solution converts to \( \frac{2^u}{\ln 2} + C \), showcasing the direct application of this rule.
Algebraic Simplification
Algebraic simplification plays a crucial role in solving integrals efficiently. This process involves reducing an expression to its simplest form, often making difficult problems easier to handle.
- In integrals, simplification can involve canceling terms, rearranging factors, or combining like terms. These steps reduce the integral to a form where known rules or techniques can be easily applied.
- During the original solution, when substituting \( u = \sqrt{y} \) and \( dy = 2u \, du \) into the integral, the terms \( 2u \) in the numerator and denominator canceled each other. This cancellation is a type of algebraic simplification that turned a complex expression into a much simpler \( \, \int 2^u \, du \, \).