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Multiple Choice
Evaluate the indefinite integral as an infinite series: .
A
+ C
B
+ C
C
+ C
D
+ C
Verified step by step guidance
1
Step 1: Begin by understanding the problem. The goal is to evaluate the indefinite integral ∫ (cos(x) - 1) x dx as an infinite series. This involves expanding the function cos(x) into its Taylor series representation and integrating term by term.
Step 2: Recall the Taylor series expansion for cos(x): cos(x) = ∑_{n=0}^{∞} (-1)^n x^(2n) / (2n)!. Subtract 1 from this series to get cos(x) - 1 = ∑_{n=1}^{∞} (-1)^n x^(2n) / (2n)! (note that the n=0 term vanishes).
Step 3: Multiply the series representation of cos(x) - 1 by x. This results in x(cos(x) - 1) = ∑_{n=1}^{∞} (-1)^n x^(2n+1) / (2n)!.
Step 4: Integrate term by term. The integral of x^(2n+1) is x^(2n+2) / (2n+2). Therefore, the integral becomes ∑_{n=1}^{∞} (-1)^n x^(2n+2) / [(2n+2)(2n)!] + C, where C is the constant of integration.
Step 5: Simplify the series expression to match the given answer format. The final result is ∑_{n=1}^{∞} (-1)^n x^(2n+1) / [(2n+1)(2n)!] + C, which is the correct answer.