For a non-negative integer nnn, [...]\text{[...]}[...], and 0!=10!=10!=1.
When order does not matter.
The number of ways to choose rrr objects from nnn distinct objects is nCr=n!r!(n−r)!\boxed{{}^nC_r=\dfrac{n!}{r!(n-r)!}}nCr=r!(n−r)!n!, where 0≤r≤n0\le r\le n0≤r≤n.
For a non-negative integer nnn, n!=n(n−1)(n−2)⋯3×2×1\boxed{n!=n(n-1)(n-2)\cdots3\times2\times1}n!=n(n−1)(n−2)⋯3×2×1, and 0!=10!=10!=1.
4!=\strong244!=\strong{24}4!=\strong24
1.3.2 Sequences and series Flashcards
Flashcards for CCEA A Level Maths 1.3.2 Sequences and series, covering the key formulae, methods and definitions you need to recall for AS 1, AS 2, A2 1 and A2 2. 25 cards, matched to the CCEA A Level Maths (2210) specification. Recall questions account for roughly 50% of marks at A Level Maths, so these target the marks you can secure before the paper starts.