The unknown number(x) in the series is 31.
The given series 1, 2, 6, 15, x, 56, 92.
We need to find the value of x.
<h3>What is a series?</h3>
In mathematics, a series is, roughly speaking, a description of the operation of adding infinitely many quantities, one after the other, to a given starting quantity. The study of series is a major part of calculus and its generalization, and mathematical analysis.
The numbers in the series increase by (n+1)².
So the sequence is 1, 1+1² (which is 2), 2+2², 6+3², 15+4², 31+5², 56+6² and the fifth term of that sequence is x=15+4²=31.
Therefore, the unknown number(x) in the series is 31.
To learn more about the series visit:
brainly.com/question/16415816.
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