Factorial/Examples/5
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Example of Factorial
- $5! = 120$
Proof
| \(\ds 5!\) | \(=\) | \(\ds 5 \times 4 \times 3 \times 2 \times 1\) | Definition 2 of Factorial | |||||||||||
| \(\ds \) | \(=\) | \(\ds 5 \times 4!\) | Definition 1 of Factorial | |||||||||||
| \(\ds \) | \(=\) | \(\ds 5 \times 24\) | Factorial of $4$ | |||||||||||
| \(\ds \) | \(=\) | \(\ds 120\) |
$\blacksquare$
Sources
- 2009: Murray R. Spiegel, Seymour Lipschutz and John Liu: Mathematical Handbook of Formulas and Tables (3rd ed.) ... (previous) ... (next): $\S 3$: The Binomial Formula and Binomial Coefficients: Factorial $n$