The binomial series
The Binomial Series
- The Binomial Theorem provides us with a way to expand any power of a binomial without needing to multiply it out.
- The general formula for the Binomial Theorem is: (a+b)^n = ∑ [(nCk) * a^(n-k) * b^k] where C stands for combination and ∑ stands for summation. These are worked out over all values of k from 0 to n.
- (nCk) is the binomial coefficient and can be calculated using factorials: n! / [(n-k)!k!]. The exclamation mark represents a factorial, which means the product of an integer and all the integers below it. For example, 5! = 5x4x3x2x1.
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The Binomial Theorem can also be used for negative or fractional powers if ** b/a < 1**. - The series would then become infinite as there will always be further terms. However, these additional terms become so small that they can be disregarded for practical purposes, hence (a+b)^n is approximated by the first few terms of the series.
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For negative or fractional n, the Binomial Expansion becomes an infinite series: (1+x)^n = 1 + nx + n(n-1)/2! * x^2 + … and so on. It only converges if ** x <1**.
Pascal’s Triangle
- Pascal’s Triangle is a simple, yet valuable tool for calculating the coefficients in the binomial expansion. The row number represents the power of the binomial, and the numbers in the row give the binomial coefficients.
- To generate this triangle, you start with the first line as [1], the second line as [1, 1] and you build additional rows where each number is the sum of the two numbers directly above it. For example, the third line will be [1, 2, 1].
Applications of the Binomial Theorem
- In Finance: The binomial model in finance is a method of evaluation of options.
- For Probability: The binomial distribution, based on the binomial theorem, is a concept in statistics used to predict the outcome of events.
- In Computer Science: Algorithms based on the binomial coefficient are used for computer programming.