How many ways to choose 2 items from 10?
How many ways to choose 2 items from 10?
Approach: n! / (k!(n-k)!).
45. (10 * 9) / 2 = 45.
Follow-up: How many ways to choose 8 from 10?
Key concepts: combinations.
How many ways to choose 2 items from 10?
Approach: n! / (k!(n-k)!).
45. (10 * 9) / 2 = 45.
Follow-up: How many ways to choose 8 from 10?
Key concepts: combinations.