Question

Whats the value of 13C11

Answer 1

Answer:

78

Step-by-step explanation:

$nC_k = \frac{n!}{k!(n-k)!}$

$13 C_{11} = \frac{13!}{11! \times (13-11)!}$

        $= \frac{13!}{11! \times 2!}$

       $= \frac{ 1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7 \times 8 \times 9 \times 10\times 11 \times 12 \times 13}{(1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7 \times 8 \times 9 \times 10\times 11 )\times ( 1 \times 2)}$

        $=\frac{12 \times 13}{2} \\\\= 6 \times 13\\\\=78$