Binomial coefficients and pascal's triangle

In summary, the conversation discusses a problem from a mathematics olympiad book where the task is to prove the relationship between n choose r, with n being the row number and r being the term number, and that specific term in Pascal's triangle. The individual is seeking a hint and mentions difficulty finding proofs online. Another participant suggests considering the random walk interpretation of Pascal's triangle and provides an alternative approach through algebraic conditions.
  • #1
Atomos
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I am working through a mathematics olympiad problem book, and I am asked to prove that n choose r, where n is the row number and r is the term number in the row is equal to that term. Can someone please give me a hint? I have not been able to find ANY proofs on the internet through a basic search, just sites that acknowledge the relationship between binomial coefficients/theorem and pascal's triangle.
 
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  • #2
It might help to recognize that each number in Pascal's triangle is equal to the total number of ways of reaching that location starting at the top and moving downward such that in going from one row to the next you can only move one step to the left or one step to the right. (Like a random walk!)
 
  • #3
Here's another way to do it:

Find some algebraic conditions that completely specify Pascal's triangle.
Prove that nCr satisfies those algebraic conditions.
 

1. What are Binomial coefficients?

Binomial coefficients, also known as combinations, are the different ways to choose a certain number of objects from a larger set. They are represented by the symbol "n choose k" or nCk, where n is the total number of objects and k is the number of objects being selected.

2. How are Binomial coefficients calculated?

The formula for calculating Binomial coefficients is nCk = n! / (k!(n-k)!), where n! represents n factorial, or n x (n-1) x (n-2) x ... x 1. Alternatively, Binomial coefficients can also be found using Pascal's Triangle.

3. What is Pascal's Triangle?

Pascal's Triangle is a triangular arrangement of numbers where each row represents the coefficients of the binomial expansion of (a+b)n. The first and last numbers in each row are always 1, and the rest of the numbers are found by adding the two numbers directly above it in the previous row.

4. How can Pascal's Triangle be used to find Binomial coefficients?

To find a specific Binomial coefficient using Pascal's Triangle, locate the row corresponding to n in nCk and count k numbers along the row. The number at this position will be the value of nCk.

5. What are some real-world applications of Binomial coefficients and Pascal's Triangle?

Binomial coefficients and Pascal's Triangle are commonly used in probability and statistics to calculate the number of possible outcomes in a given scenario. They can also be applied in fields such as genetics, computer science, and economics. For example, binomial coefficients can be used to determine the number of possible gene combinations in a genetic cross, or the number of ways to arrange a set of data in a computer program.

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