I"m act a sequences problem where I have to write the an initial five terms of a sequence. That looks normal, however there is an exclamation note on the denominator:

$$a_n = \frac1(n + 1)!$$

&

$$a_n = \frac(-1)^nnn! + 1$$

What does the exclamation mark mean, and how do I go about this differently with the exclamation mark?

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The factorial of a number is stood for by the exclamation allude (!).The factorial of a number $x$ is often described as the product of all positive integers much less then or same to $x$. For example:

$$4! = 4\cdot3\cdot2\cdot1 = 24$$

It is often likewise useful to define $x!$ in a recursive relation:

$$x! = x(x-1)!$$

where $0! = 1$.

This an approach is often good because the helps define why $0!=1$ (see also the "empty product" for an ext on this). Using the above explanation, us may uncover $4!$:

$$4! = 4(3)! = 4(3)(2)! = \cdots = 4(3)(2)(1)(0)! = 4(3)(2)(1)(1) = 24$$

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edited Apr 9 "12 at 1:29

Michael hardy
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answer Apr 9 "12 at 0:09

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If the number is 4! then you count down so it would be $4\times 3 \times 2\times 1= 24$. An additional thing is that if the number is 7! you would certainly count down till you get to two. So it would certainly be $7\times 6\times 5\times 3\times 2 =5040$ 7 x 6 x 5 x 4 x 3 x 2 I simply put in the 4 the was not listed although the prize is tho 5040.

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edited Apr 27 "16 in ~ 2:46

CommunityBot
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answered might 19 "14 at 23:03
HockeyloverHockeylover
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Hockeylover It's actually defined recursively and one "counts down" to $0! :=1$. $\endgroup$
–user137731
jan 7 "15 at 20:55

Highly energetic question. Knife 10 call (not counting the association bonus) in order to answer this question. The reputation requirement helps defend this question from spam and non-answer activity.

## Not the prize you're spring for? Browse various other questions tagged calculus real-analysis sequences-and-series notation factorial or asking your own question.

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