Chapter 7: Problem 34
Evaluate the integral. $$ \int \frac{\left(2^{x}+1\right)^{2}}{2^{x}} d x $$
Short Answer
Expert verified
\(\frac{2^x}{\ln(2)} + 2x - \frac{2^{-x}}{\ln(2)} + C\)
Step by step solution
01
Rewrite the Integrand
First, rewrite the integrand by expanding the numerator. The expression \((2^x + 1)^2\) expands to \(2^{2x} + 2 \cdot 2^x \cdot 1 + 1^2\), simplifying to \(2^{2x} + 2 \cdot 2^x + 1\). Thus, the integral becomes: \(int \left(\frac{2^{2x}}{2^x} + \frac{2 \cdot 2^x}{2^x} + \frac{1}{2^x}\right) dx\).
02
Simplify the Integrand
Simplify each term of the integrand: \(int \left(2^x + 2 + 2^{-x}\right) dx\). Notice that each term is now a simpler expression that can be integrated independently.
03
Integrate Each Term Separately
Integrate each term separately: - For \(2^x\), the integral is \(\frac{2^x}{\ln(2)}\).- For 2, the integral is \(2x\). - For \(2^{-x}\), the integral is \(-\frac{2^{-x}}{\ln(2)}\).Combine these results to find the integral of the original expression.
04
Combine Results and Add Constant of Integration
Combine the results from Step 3: \(\frac{2^x}{\ln(2)} + 2x - \frac{2^{-x}}{\ln(2)} + C\).Here, \(C\) is the constant of integration, which accounts for any constant that could have been differentiated to yield zero in the original integral.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Expansion
Polynomial expansion involves breaking down expressions into a sum of terms based on existing mathematical rules and identities. In this integral problem, we start with \((2^x + 1)^2\).To expand this polynomial, we use the algebraic identity \((a + b)^2 = a^2 + 2ab + b^2\).
For our specific polynomial:
For our specific polynomial:
- Set \(a = 2^x\) and \(b = 1\).
- Thus, \((2^x + 1)^2 = (2^x)^2 + 2(2^x)(1) + 1^2\).
- This simplifies to \(2^{2x} + 2 imes 2^x + 1\).
Integration Techniques
Integration techniques are essential tools in calculus for finding the antiderivative or integral of a function. In our example, the expression\(\frac{(2^x + 1)^2}{2^x}\)is simplified into three separate terms: \(2^x, 2,\) and \(2^{-x}\).
To integrate the function:
To integrate the function:
- The integral of \(2^x\) is \(\frac{2^x}{\ln(2)}\)because \(\ln(2)\) is the constant of integration for exponential functions with base 2.
- The integral of the constant \(2\) is straightforward as \(2x\).
- The integral of \(2^{-x}\) requires the understanding of negative exponents, resulting in \(-\frac{2^{-x}}{\ln(2)}\).
Logarithmic Functions
Logarithmic functions are the inverse of exponential functions and are crucial in integration, especially with non-standard bases like 2. In our integral example, logarithmic functions play a key role in calculating the antiderivative for \(2^x\) and \(2^{-x}\).
For base 2 exponential functions, the natural logarithm \(\ln(2)\) is used in the denominator of the antiderivative. This is because:
For base 2 exponential functions, the natural logarithm \(\ln(2)\) is used in the denominator of the antiderivative. This is because:
- The derivative of \(2^x\) is proportional to itself but multiplied by \(\ln(2)\),which means the antiderivative will include a division by \(\ln(2)\).
- Similarly, \(2^{-x}\) is integrated by including \(-\frac{1}{\ln(2)}\) since the negative exponent switches the direction of the growth.