Stumped With Evaluating 3k/k! from 0 to Infinity

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In summary, the conversation discusses a problem involving evaluating the sum of 3k/k! from 0 to infinity. The suggested strategy is to use the geometric series formula with r=3/k. The conversation also mentions finding f'(x) and how it relates to f(x). The function f(x) can be determined by looking at its Taylor series, and the final answer is f(3). The conversation also mentions a hint about the binomial formula, causing some confusion.
  • #1
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I've been staring at this stupid problem for a while, and finally gave up and came here. The question is to evaluate the sum of 3k/k! from 0 to infinity. Basically, I'm looking for a starting spot, since I have none. The closest thing to a strategy I've come up with is plugging it into the geometric series formula with r=3/k, but that didn't work so well :uhh:
 
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  • #2
Let

[tex]f(x) = \sum_{k=0}^{\infty}\frac{x^k}{k!}[/tex]

What is f'(x)? In particular, how does f'(x) relate to f(x)? What other functions relate to their derivatives in that way? If you know some stuff about differential equations, you'll know that only one type of function relates to its derivative in that way. So you can figure out what type of function f(x) is, and by plugging in x=0, you get an initial value problem which allows you to find what function f(x) is specifically. Once you know what f is, your final answer is f(3).
 
  • #3
Actually, if you have worked with Taylor's series, you ought to be able to look at that series and recognize it immediately. If not, AKG's suggestion is excellent: take the derivative, term by term, then slap your forehead and say "oh, of course!".
 
  • #4
After mentioning taylor's series, it's pretty obvious... unfortunately, for some obnoxious reason right before the question there was a hint about the binomial formula, so I got the impression it was supposed to be involved with that somehow. (especially since the three questions after it were).

Thanks
 
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1. What is the significance of evaluating 3k/k! from 0 to Infinity?

Evaluating 3k/k! from 0 to Infinity is a common mathematical problem that has many applications in fields such as statistics, probability, and physics. It involves finding the value of the infinite series 3k/k!, where k represents any positive integer starting from 0. This problem is often used to calculate probabilities of events occurring in a certain sequence or to model exponential growth.

2. How do you solve the problem of evaluating 3k/k! from 0 to Infinity?

The problem of evaluating 3k/k! from 0 to Infinity can be solved using various mathematical techniques such as the Taylor series expansion, the binomial theorem, and the ratio test. The solution involves finding the limit of the infinite series, which can be simplified using these techniques to get a final answer.

3. Is there a closed-form solution for evaluating 3k/k! from 0 to Infinity?

Unfortunately, there is no known closed-form solution for evaluating 3k/k! from 0 to Infinity. This means that the infinite series cannot be expressed in terms of a finite number of mathematical operations or functions. Instead, it can only be approximated using numerical methods or by using the first few terms of the series.

4. How is evaluating 3k/k! from 0 to Infinity related to factorial notation?

Evaluating 3k/k! from 0 to Infinity is closely related to factorial notation because the series 3k/k! can be rewritten as 3k/(k)(k-1)(k-2)...(2)(1), which is the definition of k!. This notation is often used in combinatorics and probability to represent the number of possible arrangements or combinations of a given set of objects.

5. What are some real-world applications of evaluating 3k/k! from 0 to Infinity?

The problem of evaluating 3k/k! from 0 to Infinity has many real-world applications, such as in calculating the probability of multiple independent events occurring in a specific order, modeling population growth, and predicting the spread of diseases. It is also used in various fields of science and engineering, including physics, chemistry, and computer science.

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