Math Problem Statement

Given that $\binom{15}{8}=6435$, $\binom{16}{9}=11440$, and $\binom{16}{10}=8008$, find $\binom{15}{10}$.

Solution

We are given the values of the binomial coefficients:

(158)=6435,(169)=11440,(1610)=8008\binom{15}{8} = 6435, \quad \binom{16}{9} = 11440, \quad \binom{16}{10} = 8008

We are tasked with finding (1510)\binom{15}{10}. Using Pascal's identity, we know:

(nk)=(n1k1)+(n1k)\binom{n}{k} = \binom{n-1}{k-1} + \binom{n-1}{k}

Applying this to (1610)\binom{16}{10}, we have:

(1610)=(159)+(1510)\binom{16}{10} = \binom{15}{9} + \binom{15}{10}

Thus,

8008=(159)+(1510)8008 = \binom{15}{9} + \binom{15}{10}

Additionally, using Pascal's identity again on (169)\binom{16}{9}:

(169)=(158)+(159)\binom{16}{9} = \binom{15}{8} + \binom{15}{9}

Substituting the known values:

11440=6435+(159)11440 = 6435 + \binom{15}{9}

Solving for (159)\binom{15}{9}:

(159)=114406435=5005\binom{15}{9} = 11440 - 6435 = 5005

Now, substitute (159)=5005\binom{15}{9} = 5005 into the equation for (1610)\binom{16}{10}:

8008=5005+(1510)8008 = 5005 + \binom{15}{10}

Solving for (1510)\binom{15}{10}:

(1510)=80085005=3003\binom{15}{10} = 8008 - 5005 = 3003

Thus, (1510)=3003\binom{15}{10} = 3003.


Would you like more details or have any questions? Here are some related questions you might find helpful:

  1. How can Pascal’s identity be used to derive other binomial coefficients?
  2. What is the significance of symmetry in binomial coefficients?
  3. How can we express (nk)\binom{n}{k} in terms of factorials?
  4. How does Pascal’s triangle visually represent binomial coefficients?
  5. Can we derive (1610)\binom{16}{10} directly using factorials?

Tip: Symmetry in binomial coefficients means that (nk)=(nnk)\binom{n}{k} = \binom{n}{n-k}. This can simplify many computations!

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Math Problem Analysis

Mathematical Concepts

Combinatorics
Binomial Coefficients
Pascal's Identity

Formulas

Pascal's Identity: \( \binom{n}{k} = \binom{n-1}{k-1} + \binom{n-1}{k} \)

Theorems

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Suitable Grade Level

Advanced High School