Askiitians Tutor Team
Last Activity: 4 Months ago
To tackle the infinite series you've presented, we need to break it down step by step. The series can be expressed as:
Understanding the Series
The series is given by:
S = 2 - \frac{2^2}{2} + \frac{2^3}{3} - \frac{2^4}{4} + \frac{2^5}{5} - \ldots
This can be rewritten in a more general form as:
S = Σ (-1)^(n+1) * (2^n / n) for n = 1 to ∞
Identifying the Pattern
In this series, each term alternates in sign, and the numerator grows exponentially while the denominator grows linearly. This is a classic form of an alternating series, which can often converge to a specific value.
Using the Taylor Series
One way to analyze this series is to relate it to the Taylor series expansion of the natural logarithm function. The Taylor series for ln(1+x) is:
ln(1+x) = Σ (-1)^(n+1) * (x^n / n) for |x| < 1
By substituting x = 2, we can see that our series resembles this form. However, since x = 2 is outside the radius of convergence for the natural logarithm, we need to be cautious.
Convergence of the Series
To determine if our series converges, we can apply the Alternating Series Test. This test states that if the absolute value of the terms decreases monotonically to zero, the series converges. In our case:
- The terms are of the form 2^n/n.
- As n increases, the terms do not decrease to zero because the exponential growth of 2^n outpaces the linear growth of n.
Thus, the series diverges. This means that as we sum more and more terms, the total does not approach a finite limit.
Conclusion on the Series
In summary, the series you provided diverges due to the rapid growth of the exponential terms compared to the linear denominator. While it may seem like it could converge at first glance, the behavior of the terms shows that they do not approach zero, leading to divergence. If you have any further questions or need clarification on any part of this explanation, feel free to ask!