Question

I need help plz..... ☺

Answer 1

It's 42, here's a quick trick to do this, so we know there's 7 movies, and to find the combination we know we can't choose 2 of the same movie, so to make this part easier , in your head take one movie from the stack out of the stack now there's 6 movies. It's now just the "plug and play" step , (7)*(6)=(42)
I'm sorry If this is to long of an explanation, but I hope that this helps you understand on how to do this problem. Have a nice day :)

Answer 2

Use factorials to solve this question.

When you are choosing multiple items out of a set, the permutation formula will be represented by the following:

$\frac{n!}{(n-r)!}$

n represents the total amount of items, and r represents the number of items you're choosing from the set.

The stack has 7 items, and you are choosing sets of 2 items from the stack. Plug the values into the formula:

$\text{n = 7, r = 2}$
$\frac{7!}{(7-2)!} = \frac{7!}{5!} = \boxed{42}$

There will be 42 different combinations to choose from.