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For a non-negative integer nnn, [...]\text{[...]}[...], and 0!=10!=10!=1.
A
When order does not matter.
B
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.
C
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.
D
4!=244!=\boldsymbol{24}4!=24
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1.3.2 Sequences and series Flashcards
25 flashcards on CCEA A Level Maths 1.3.2 Sequences and series: the key formulae, methods and definitions you need to recall for AS 1, AS 2, A2 1 and A2 2.