How to Calculate Pascal's Triangle
What is Pascal's Triangle?
Pascal's Triangle is a triangular array where each number is the sum of the two numbers directly above it. It encodes binomial coefficients, combinatorics, and the coefficients of binomial expansions. Named after Blaise Pascal (1623–1662) though known much earlier.
Step-by-Step Guide
- 1Row 0: 1 | Row 1: 1, 1 | Row 2: 1, 2, 1 | Row 3: 1, 3, 3, 1
- 2Entry C(n,k) = entry in row n, position k = n! / (k!(n−k)!)
- 3Binomial expansion: (a+b)^n coefficients are row n of the triangle
- 4Sum of row n = 2^n; diagonal sums give Fibonacci numbers
Worked Examples
Input
(x+y)^4
Result
1x⁴ + 4x³y + 6x²y² + 4xy³ + 1y⁴
Coefficients: Row 4 = 1,4,6,4,1
Input
Combinations C(5,2)
Result
10
Row 5, position 2 of Pascal's Triangle
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