## Esmy 3 years ago 17C4

1. ParthKohli

$$\color{Black}{\Rightarrow\Large {17! \over (17 - 4)! 4!} }$$

2. Esmy

|dw:1342190004971:dw| A. 2,380 B. 680 C. 57,120 D. 4,760

3. ParthKohli

Can you do the rest with a calculator?

4. Esmy

I got D I'm i right

5. ParthKohli

$$\color{Black}{\Rightarrow\Large {17 \times 16 \times 15 \times 14 \over 24} }$$

6. ParthKohli

Let me check it.

7. lgbasallote

hmm

8. ParthKohli

Hmm no. But I can explain how I reached that step.

9. Esmy

17C4 = 17! / ( 4! (17 - 4)! ) 17C4 = ( 17! ) / ( 4! * 13! ) 17C4 = (17 * 16 * 15 * 14) / (4 * 3 * 2 * 1) 17C4 = 2380

10. moha_10

(17-4)! how to simplify this

11. ParthKohli

$$\color{Black}{\Rightarrow \Large \binom{17}{4} = {17! \over (17 - 4)! 4!} }$$

12. Esmy

I got that now :/ ? I'm not sure if I did it right.

13. lgbasallote

yes you did

14. ParthKohli

$$\color{Black}{\Rightarrow\Large {17! \over 13!4!} }$$

15. lgbasallote

amazingly a sciientific calculator already has a function for this lol

16. lgbasallote

you just have to push buttons =)) but yeah learning this process is better

17. Esmy

lol okay yeah I was just wondering ^ ^ needed to know my work was good.

18. ParthKohli

$$\color{Black}{\Rightarrow\Large {\cancel{17!}^{17 \times 16 \times 15 \times 14} \over \cancel{13!}4!} }$$

19. lgbasallote

it was well

20. ParthKohli

Yep it was great!

21. lgbasallote

do you have a scientific calculator though @Esmy ?

22. ParthKohli
23. Esmy

yes.

24. lgbasallote

you can check your work through that

25. ParthKohli

I have a Ti - 30XA which is pretty well.

26. lgbasallote

do you see a function that says $nCr$

27. ParthKohli

But nobody can beat wolfram ♥

28. lgbasallote

try pressing $17 \rightarrow nCr \rightarrow 4$ see the magic happen

29. ParthKohli

You have to press $$17 \Longrightarrow 2nd \Longrightarrow 8 \Longrightarrow 4$$ on this one.

30. Esmy

Oh okay I got it ^ ^ thanks tho for your help.

31. lgbasallote

dont you mea 2ndF?

32. lgbasallote

mean*

33. ParthKohli

You just have to type out 17C4 on Wolfram.

34. ParthKohli

All scientific calculators differ.

35. lgbasallote

i've never heard of a function that says 2nd only though

36. ParthKohli

$$\text{WolframAlpha} > \text{A boring and tedious scientific calculator}$$

37. lgbasallote

usually it's 2ndF or shift

38. lgbasallote

bringing calculator > bringing iPad lol

39. ParthKohli

Typing http://wolframalpha.com > bringing a scientific calculator. :P