A-Level Maths: D1-02 [Binomial Expansion: Explaining where nCr comes from]

[VK-ilkv]

ur explaining things that even my teacher didnt say....apprecaite it lots

[jackwilliams]

I watched this before starting binomial expansion then today struggled with a more abstract binomial expansion problem, I came back to revise this video and I just want to say you explained it really well. Thanks!

[ashcraft]

I’m sitting here during an online lesson watching this instead cause my teacher didn’t explain it lol

[lukeollerhead]

absolutely critical video if your ambition is to actually understand the content. Great stuff.

[julianredding-mcfadden]

so well explained. the analogy makes it so clear. Thank you so much!!

[mayambanassar]

Thanks allot. I never understood my teacher all the time during this topic. But you just explained once and I got it all the way. Thank you for sharing your video wiht us. 🙏🙏🙏🙏🙏🙏🙏 May u shine forever

[zoe]

n! = permutations of the total amount of people
r! = permutations of repeated patterns left over after 4 chairs are removed
(n-r)! = permutations of people left over when 4 chairs are removed
is it ok to break it down like that?
so one would be of the possible patterns that would be excluded after the chairs are removed and the other would be of possible patterns for the people left over

i feel like im overcomplicating it

[mayambanassar]

You explain more than my subject teacher

[tanushrikaluarachchi]

I'm so happy you made these videos because I missed this lesson and I was so confused

[NUFCTheToon]

These videos might just save me. You’re amazing man

[neilmccafferty]

should have used five chairs to be completely unambiguous. Still the best tutor on line by miles.

[-Berry.]

Is it necessary to learn that binomial equation with the exclamation mark? Could you just know nCr?

[nonamesleft]

5:00 how is there 24 to many? Wouldn’t it be 8x7x6x5. Because there are 4 seats, 8 people in total, which decrease by 1. Is that there is a repetition ex: ABCD DCBA. So you divide by 4! But then why wouldn’t you just divide by 2? That’s the only part of confusion but the rest is great thank you

[apurbosaha]

When dividing by 4! which removes 24 ways of reordering ABCD, wouldn’t you only need to remove 23 ways of reordering as you would need to keep 1 combination?

[katana]

What about the repeated combinations from A B C E OR A B C G or any others

[yaboy]

If dividing by 4! eliminates the 24 ways of re-ordering ABCD, shouldn't we need to divide by more than 4! to eliminate all the ways of reordering ABCDEFGH?

[javine]

I am confused as to why you have to divide by r!