## gjhfdfg Group Title Evaluating expressions, one year ago one year ago

1. gjhfdfg Group Title

Easiest problem ever, but I forgot how to do them, |dw:1361117139126:dw| Can someone show me step by step how to solve this or create a problem giving me an example? Thanks.!

$1-\frac{ 694 }{ 896 }$ do you mean?

3. gjhfdfg Group Title

No, its P

then p4 do you mean its power or 4 is multiplied?

like p4 or $p^4$

6. gjhfdfg Group Title

I have no idea... It just says 6P4,

7. gjhfdfg Group Title

Noo, its not that, I'll take a screenshot

ok... i am waiting for screenshot.

9. gjhfdfg Group Title

This is the problem,

this is Permutation.

11. hartnn Group Title

ohh..its permutation!

12. gjhfdfg Group Title

I also have this problem that includes a exclamation mark, |dw:1361117585779:dw| Do you know what its for?

13. gjhfdfg Group Title

& whats permutation? O_O I have never ever heard of that

14. hartnn Group Title

$$!$$ means a factorial.

15. hartnn Group Title

$$n!= n(n-1)(n-2).......3.2.1$$ when n is a whole number. like for example 5! = 5*4*3*2*1 = 120

answer is 1 it means that you need to expand 6 as 4 times and 8 as 6 times.

1/56

18. hartnn Group Title

before getting to permutation, you should know what a factorial ! is .

19. gjhfdfg Group Title

OH.! so I had something like 10! I would have to do 10*9*8*7*6*5*4*3*2*1= etc..?

20. hartnn Group Title

yes, thats correct.

6P4= 6*5*4*3 and 8P6= 8*7*6*5*4*3

yes you are correct.

23. hartnn Group Title

do you want to know how to get that^ ?

24. gjhfdfg Group Title

I feel like I've done this stuff in 8th grade but had forgotten how to do some of this. These questions are for my pre-cal class & I found it odd that I had a probability question in there

yes.

26. hartnn Group Title

$$\huge ^nP_r = \dfrac{n!}{(n-r)!}$$

27. gjhfdfg Group Title

So basically I had to do the factorial (!) to the 6P & 8P?

yes.

29. hartnn Group Title

$$\huge ^nP_r = \dfrac{n!}{(n-r)!} \\\huge ^6P_4 = \dfrac{6!}{(2)!} \\ \huge 8P_6 = \dfrac{8!}{(2)!}$$

30. gjhfdfg Group Title

Everything on the left side of the = is confusing to me

31. hartnn Group Title

in the formula of nPr ? its just a formula, so for 6P4, i plugged in n=6 and r=4 in the standard formula.

32. gjhfdfg Group Title

How would you know which ones to plug in? Because in one you have 6P4 & in the next 8P6, I don't get how you go to that?

33. hartnn Group Title

n is before P , r is after P . in 6P4 , 6 is before P (so, n=6) and 4 is after P (so r=4) does this makes sense ?

34. gjhfdfg Group Title

Ah, it does now.! :-) Thanks you guys both for explaining this to me.!

35. hartnn Group Title

Thank me when you get to correct answer.

36. gjhfdfg Group Title

What do you mean?

37. hartnn Group Title

i meant to ask you, whether you could now figure out the answer of that question...

38. gjhfdfg Group Title

I do the factorial, 8*7*6*5*4*3*2*1, I thought?

39. gjhfdfg Group Title

& then divide my answer by 2?

40. hartnn Group Title

thats for 8P2

41. gjhfdfg Group Title

Then I'm lost again,

42. hartnn Group Title

i never said you are wrong. its just not the final answer.

43. gjhfdfg Group Title

Then I do the same with the 6

44. hartnn Group Title

6P4 = 6*5*4*3 8P2= 8*7*6*5*4*3 Question asks, 1- 6P4/8P2 = 1- 6*5 / 8*7*6*5 = 1- 1/(8*7) ok ?

45. gjhfdfg Group Title

Ah, I wasnt paying attention to the 1,

46. gjhfdfg Group Title

Would I have to subtract the 1 from the 6 & start factoring 5?

47. hartnn Group Title

no... first division operation is performed, so 6*5*4*3 will get cancelled from numerator and denominator, and what remains is just 1- 1/(8*7) which i've already shown.

48. gjhfdfg Group Title

Thats confusing

49. hartnn Group Title

ok, clear till this : 6P4 = 6*5*4*3 8P2= 8*7*6*5*4*3

50. gjhfdfg Group Title

Got that...

51. hartnn Group Title

now divide them 6P4/8P2 =.... ?

52. gjhfdfg Group Title

I got 0.0178 etc... Thats not right..

53. hartnn Group Title

keep it in fractions..

54. gjhfdfg Group Title

I got 360 from 6*5*4*3 & 20160 from the factorial of 8.

55. gjhfdfg Group Title

How would I keep it in fractions?

56. hartnn Group Title

you can also cancel out like this : |dw:1361120576575:dw| got that ?

57. gjhfdfg Group Title

Ah, got it.! I wasnt thinking about canceling out

58. hartnn Group Title

59. gjhfdfg Group Title

What happened to the 4 & 2?

60. hartnn Group Title

i just realized i mistyped 8P6 (and have written 8P2 instead) 4 and 2 where ?

61. gjhfdfg Group Title

The 4 after the P and the 2 after the other P

62. hartnn Group Title

oh, we used the formula, right ? 6-4 = 2, so 2! in the denominator 8-6= 2, so 2! in the denominator

63. gjhfdfg Group Title

OH.! Ok I get it.!

64. gjhfdfg Group Title

1/56 wasnt correct, could it be 55/56 by any chance?

65. hartnn Group Title

?? you forgot '1-...' again ? 1- 1/(7*8)= 1-1/56=(56-1)/56 = 55/56

66. gjhfdfg Group Title

*face palm* Thank you.

67. hartnn Group Title

welcome ^_^