Algebra

posted by .

It's been so long since I've donw combinations, and now I have a question about them in my algebra homework packet. Question is....Marcie has a collection of 9 DVDS. She will choose 4 of them to take in the car to watch during a long trip. How many combinations of 3 DVDS can Marcie take from her collection ? 504, 252, 168, or 84 ?

• Algebra -

Please clarify if she is taking 3 or 4. You say both numbers.

If she is taking 4, the answer is
9!/(4!*5!) = 9*8*7*6/(1*2*3*4)
= 9*8*7/4 = 126

If she is taking 3, the answer is
9!/(3!*6!) = 9*8*7*6/3! = 9*8*7 = 504

Similar Questions

1. Algebra I

So- im trying to help my little brother out with his Algebra- but its been awhile since i have had algebra class- we need help with the following question: Solve the following equation for x: 2(x+4)=4x+12 2x+8=4x+12 2x=-4 x=-2 I think, …
2. Algebra

Hi jiskha! I was wondering if anyone could answer this ~fun~ question. f(x)=5x^2-2x+3 and g(x)=4x^2+7x-5. I have to find f+g. For my answer, I got 12x^4+-2x+-2, while the answers in my packet said 9x^2+5x-2. Could anyone explain this?
3. math (college algebra)

Ok I have two questions I have NO CLUE how to complete on my homework. Please help ASAP! (1) Solve the formula for the specified variable r = vx for r (the question is) v = ?
4. algebra

At a local ice cream shop, you can choose from a collection of 18 different toppings. If you want to choose at least one topping, how many different topping combinations are possible (assuming no repeat toppings)?
5. Math

How long can I wait to see the answer of my question about Algebra ?
6. algebra

Bob is going to China, and he wants to bring some DVDs on the airplane. If Bob has a collection of DVDs, in how many ways can he bring of them?