Question

What is _10C_8 ?
(The 10 and 8 are subscripts next to the C, thanks!)

Answer 1

\(\displaystyle_{10}C_{8} = \binom{10}{8} = \dfrac{10!}{8!~2!} = \dfrac{10\cdot9\cdot8\cdot7\cdot6\cdot5\cdot4\cdot3\cdot2}{8\cdot7\cdot6\cdot5\cdot4\cdot3\cdot2\cdot2} \\~\\~\\\quad\quad~= \dfrac{10\cdot9\cdot\cancel{8}\cdot\cancel{7}\cdot\cancel{6}\cdot\cancel{5}\cdot\cancel{4}\cdot\cancel{3}\cdot\cancel{2}}{\cancel{8}\cdot\cancel{7}\cdot\cancel{6}\cdot\cancel{5}\cdot\cancel{4}\cdot\cancel{3}\cdot\cancel{2}\cdot2} \\~\\~\\\quad\quad~= \dfrac{10\cdot9}{2} \\~\\~\\\quad\quad~= \cdots~?\)

Answer 2

90/2

Answer 3

(45)

Answer 4

Yeah, what is \(\dfrac{90}{2}\) equal to?

Answer 5

yep answer is 45

Answer 6

thanks!

Answer 7

Do you understand what I did?

Answer 8

Yea i do now, i looked at the work you did at the top with the descending numbers, thanks!

Answer 9

Ok glad I helped!