Prove that the rᵗʰ term in the nᵗʰ row of Pascal's triangle is nCr.

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SUMMARY

The rᵗʰ term in the nᵗʰ row of Pascal's triangle is definitively represented by the binomial coefficient nCr, calculated using the formula n!/r!(n-r)!. The discussion emphasizes the use of mathematical induction as a robust method to prove this relationship. Participants suggest starting with the base case of (x + y)^1 and assuming the formula holds for (x + y)^n to demonstrate its validity for (x + y)^(n+1). This approach effectively utilizes the properties of Pascal's triangle, particularly the summation of adjacent entries.

PREREQUISITES
  • Understanding of binomial coefficients and the nCr formula
  • Familiarity with Pascal's triangle and its properties
  • Knowledge of mathematical induction as a proof technique
  • Basic algebraic manipulation skills
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  • Study the principles of mathematical induction in depth
  • Explore the derivation and applications of the binomial theorem
  • Learn about combinatorial proofs related to Pascal's triangle
  • Investigate the relationship between binomial coefficients and combinatorial counting
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Mathematicians, educators, students studying combinatorics, and anyone interested in the properties of Pascal's triangle and binomial coefficients.

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Prove that the rᵗʰ term in the nᵗʰ row of Pascal's triangle is nCr.



nCr formula: n!/r!(n-r)!



I've tried everything I can but I don't know how to approach this question.
 
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Have you tried induction?

You might try (x + y)^1 show that the coefficients are 1 and 1; and then assume it's true for (x+y)^n and show if that is true then it works for the row (x + y) ^(n+1).

I haven't tried that; but it would be my first try.
 
I would go with JimRoo's first suggestion, induction. You haven't said what definition you have for the terms in Pascal's triangle. I assume it's summing pairs of adjacent entries in one row to generate the next. Use that.
 

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