Question

How many ways can we write a list of 6 numbers from (1, 2, 3, 4, 5, 6, 7, 8) without repeating any?

Answer 1

Step-by-step explanation:

Number of combinations:

`C_(8)^6 = (8!)/((8-6)!*6! ) = (6!*7*8)/(2!*6! ) = (7*8)/(1*2) = (56)/(2)=28`

Answer 2

Step-by-step explanation:

`\binom{n}{\\ k} = \binom{6}{8} = (8 * 7 * 6 * 5 * 4 * 3)/(6 * 5 * 4 * 3 * 2) = 28`

We divide by factorial of 6 (!6) what is 6×5×4×3×2×1 so that there is no repetition.