Chapter 9: Problem 74
Evaluate the integral. \(\int e^{1+\ln 5 x} d x\)
Short Answer
Expert verified
The integral evaluates to \(\frac{5ex^2}{2} + C\).
Step by step solution
01
Simplify the Integrand
First, observe that the integrand is in the form of an exponential function. We have \(e^{1 + \ln(5x)}\). Using the property of exponents, \(e^{a+b} = e^a \cdot e^b\), we can simplify this to \(e \cdot e^{\ln(5x)}\). Since \(e^{\ln(a)} = a\), it follows that \(e^{\ln(5x)} = 5x\). This means the integrand can be simplified to \(5xe\), where \(e\) is a constant.
02
Factor Out the Constant
Now, write the integral with the simplified integrand: \[ \int e (5x) \, dx = e \int 5x \, dx. \]Since \(e\) is a constant, it can be factored out of the integral:\[ e \int 5x \, dx. \]
03
Integrate the Remaining Function
The integral \(\int 5x \, dx\) can be solved using basic integration rules. The integral of \(x\) is \(\frac{x^2}{2}\), so:\[ \int 5x \, dx = 5 \cdot \frac{x^2}{2} = \frac{5x^2}{2}. \]
04
Multiply by the Constant
Recalling that we factored out \(e\) in Step 2, now multiply it back to the result of the integration:\[ e \cdot \frac{5x^2}{2} = \frac{5ex^2}{2}. \]
05
Add the Constant of Integration
Since we're evaluating an indefinite integral, we must include the constant of integration, \(C\). Therefore, the final solution is:\[ \frac{5ex^2}{2} + C. \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exponential Functions
Exponential functions are a type of mathematical function characterized by the constant base raised to a variable exponent. They are expressed in the form of \( f(x) = b^x \), where \( b \) is a constant and \( x \) is the exponent.Exponential functions often appear in many natural phenomena, such as population growth, radioactive decay, and continuously compounding interest. In calculus, the exponential function \( e^x \) is particularly significant, where \( e \) is the Euler's number, approximately 2.718.
- Exponential functions are unique because their rate of growth is proportional to their current value.
- They can be combined with logarithms, due to their inherent inverse relationship, for simplification.
Integration Rules
Integration is the process of finding the integral of a function, which is essentially the reverse of differentiation. There are several rules that simplify the integration of functions, making it a more approachable task. Here are some key rules:
- Constant Multiple Rule: This rule states that a constant can be factored out of an integral, which simplifies calculations. For example, \( \int c \cdot f(x) \, dx = c \int f(x) \, dx \).
- Power Rule for Integration: The integral of \( x^n \) is \( \frac{x^{n+1}}{n+1} + C \), where \( n eq -1 \). This is used in the solution to integrate \( 5x \), resulting in \( \frac{5x^2}{2} \).
Constant of Integration
When we compute an indefinite integral, it represents a family of functions, each differing by a constant. This concept is captured by the "constant of integration," symbolized by \( C \).This constant arises because differentiation of any constant is zero, thus the integral of a function cannot determine this constant. Here's why \( C \) is crucial:
- It represents the entire set of antiderivatives.
- In contexts involving initial conditions or boundaries, \( C \) allows for the determination of a specific solution.
- Neglecting \( C \) can lead to inaccuracies, especially in applications involving precise conditions.