Maths Question (I call ALL the Geniuses)

Moneyboi · 05-05-08, 03:14 PM

Ok i was doing some work and came across this:

Find the Nth Term For : 5, 6, 8, 11, 15

Anyone Know how to work this out?#

Thanks In Advance

arcticfox · 05-05-08, 03:17 PM

20? lol

ah dinnae ken

sahou · 05-05-08, 03:18 PM

Well I can see it's +1 +2 +3 +4 +5 +6 +7 etc if that helps...?

Sephora · 05-05-08, 03:20 PM

5+(n-1)!

where ! is factorial

i.e
1!=1
2!=1+2
3!=1+2+3

never mind; got it wrong - factorial is multiply; doh

bmh16 · 05-05-08, 03:20 PM

i hate these too. i think sahou has the right idea, but how to put that into an answer...

djgallagher · 05-05-08, 03:25 PM

think this might be GCSE stuff which is going back a bit but il have a go:

1st term of n = 5
2n = 8
3n = 11
4n=15

I could be wrong but i think the nth term is expressed by = n + (n-1) which is basically the term in the sequence plus the number in the sequence before it.

Eg 3rd term would be = 3 + (2nd term of 8) = 11 which is correct

andy5 · 05-05-08, 03:30 PM

5+ (n/2)*(n-1)
or
0.5*n^2 - 0.5*n + 5

Sephora · 05-05-08, 03:32 PM

Quote:

Originally Posted by andy5

5+ (n/2)*(n-1)
or
0.5*n^2 - 0.5*n + 5

yeah, that was the one - well done!

Moneyboi · 05-05-08, 03:35 PM

Quote:

Originally Posted by andy5

5+ (n/2)*(n-1)
or
0.5*n^2 - 0.5*n + 5

Thanks How did you work that out?

andy5 · 05-05-08, 03:54 PM

this isn't how i did it but i believe you can use this formulae

a + (n-1)d + 0.5(n-1)(n-2)C

Where a is the first term
d is the difference between the first term and second term
C is the difference increase

So in this case...
a=5
d= 1
for C 5 6 8 11 15
difference 1 2 3 4 so C=1
then you put the numbers into the equation and simplify

this may only work for changing difference formuales... cant really remember

**the_icks** · 05-05-08, 04:05 PM

Simmo · 05-05-08, 04:06 PM

Aye, what they said was right. However, if the difference is the same then you use this formula which is much easier.

nth term = dn + (a - d)

**the_icks** · 05-05-08, 04:07 PM

Moneyboi · 05-05-08, 04:12 PM

Quote:

Originally Posted by the_icks

.

Why have you posted this? Twice? Also thanks for everyones help!!

arcticfox · 05-05-08, 04:14 PM

Quote:

Originally Posted by Moneyboi

Why have you posted this? Twice? Also thanks for everyones help!!

because you can only edit posts, you cant delete them. so, its the easiest way

05-05-08, 03:14 PM	#1
Moneyboi iPod Nano 4GB Join Date: Nov 2007 Posts: 257	Maths Question (I call ALL the Geniuses) Ok i was doing some work and came across this: Find the Nth Term For : 5, 6, 8, 11, 15 Anyone Know how to work this out?# Thanks In Advance

05-05-08, 03:17 PM	#2
arcticfox blah blah blah Join Date: Nov 2005 Location: Here Posts: 18,023	Re: Maths Question (I call ALL the Geniuses) 20? lol ah dinnae ken __________________ Free Nintendo 3DS Free iPhone 4 Free PS3 Free iPad 2

05-05-08, 03:18 PM	#3
sahou iPod Shuffle Join Date: Mar 2008 Location: Shropshire Posts: 26	Re: Maths Question (I call ALL the Geniuses) Well I can see it's +1 +2 +3 +4 +5 +6 +7 etc if that helps...?

05-05-08, 03:20 PM	#4
Sephora Mini Mac Join Date: Jan 2008 Location: Nottingham Posts: 3,088	Re: Maths Question (I call ALL the Geniuses) 5+(n-1)! where ! is factorial i.e 1!=1 2!=1+2 3!=1+2+3 never mind; got it wrong - factorial is multiply; doh __________________ *Total of Freebies I've Received :* view list of items in my profile Spoiler Last updated in early 2009; cba anymore Custom Orders: £14,098 Vouchers: £1789 Bank Transfers: £16,904 = £32,791 Items Received: iPod Shuffle \| Mopod \| Noise Magnets \| Nintendo Wii \| Police Mens Watch \| Wii Fit \| Wii Remote \| 2GB Zen Stone \| loads of Toys from AnaraToys \| DKNY watch \| Wii Nunchuck \| Tom Tom One Europe \| Karcher \| x2 Quinny Zapp Pushchairs \| x2 Tripp Trapp highchairs & baby kit \| Maxi Cosi car seat & cover \| Trunki \| Grobag \| Dyson DC23 Animal \| Playmobil & Lego sets \| Arthur Price cutlery & canteen \| Bvlgari charms bracelet & pendant \| La Rochere Glasses & Bowls \| Large Wheely Bug \| Tiffany & Co bracelet \| Wii Family Ski & Mario Kart \| Floor & ceiling lights \| Dog clippers & toys \| Children's books \| 4kg Soapnuts & etc \| Crayola Kits \| Biorb Fish Tank & bits \| Kids Birthday Party stuff \| iPod Shuffle \| Hipp Organic stuff \| Vax V-125 \| Loads of Carpet Washing Solutions \| Tiffany & Co bracelet \| Actifry \| Breadmaker & Bread Recipe Book \| Halloween Stuff \| Hipp Baby Milk \| Biorb Filters \| Le Creuset Wok, Blender, Kettle, & other kitchen stuff \| Dishwasher & stock of tablets, etc \| Flowers \| Playmais stuff \| Pillows \| Smeg FAB32 Fride/Freezer \| Glasses for me & hubby \| Toys from Amazon \| Books \| More Hipp Baby Milk \| Bathroom laminate flooring etc \| Shirts \| Lush stuff & gift sets \| Wooden Kitchen Combo & more Toys \| Corolle Doll & Accessories \| Amazon Vouchers \| Le Creuset drizzlers \| Playmobil Advent Calendars \| Digital Frame \| Leapfrog Tag \| Yoghurt Maker etc \| Discovery Dome and more Toys \| Small Kitchen Bits \| Tag & Books \| Micro Scalextric James Bond \| KitchenAid Accessories \| Cheese Set, Foot Massager, xmas gifts etc \| Books, DVD & Toys \| Tiffany & Co Bowl \| Punch bag \| Mugs \| SMEG Fireplace \| Ready Bed \| 5x Kids' Kickers \| Radley Bag \| Paint \| Books \| Mugs \| Cross Trainer & Flooring Protection \| Buggy Solar Shade \| iPod Classic 160GB \| iPod Dock \| Karcher and Camera for MIL \| Fireproof Safe \| Tanita Scales \| Hunter Wellies \| Travel Guides, books etc \| Kodak Picture Frame \| Bunch of activity books/stickers etc \| Kitchen Scales and Kitchen accessories \| Sylvanian Families Treehouse and all accessories etc \| Corolle Dolls Stuff and Barbies etc \| More Hipp Baby Milk \| Clickstart stuff, mug, etc \| Books, playcash, spatula, bilingual calendar, potty \| Leapfrog fridge words, stickers, games, etc \|

05-05-08, 03:20 PM	#5
bmh16 Call me Ben .... Join Date: Apr 2006 Location: Bristol / Neath Posts: 7,738	Re: Maths Question (I call ALL the Geniuses) i hate these too. i think sahou has the right idea, but how to put that into an answer... __________________ FREE PS3 \| FREE iPod Touch \| FREE Wii Spoiler

05-05-08, 03:25 PM	#6
djgallagher BANNED Join Date: Apr 2007 Location: Nr Blackpool Posts: 251	Re: Maths Question (I call ALL the Geniuses) think this might be GCSE stuff which is going back a bit but il have a go: 1st term of n = 5 2n = 8 3n = 11 4n=15 I could be wrong but i think the nth term is expressed by = n + (n-1) which is basically the term in the sequence plus the number in the sequence before it. Eg 3rd term would be = 3 + (2nd term of 8) = 11 which is correct

05-05-08, 03:30 PM	#7
andy5 iPod Nano 2GB Join Date: Mar 2008 Location: Hertfordshire or sheffield Posts: 172	Re: Maths Question (I call ALL the Geniuses) 5+ (n/2)(n-1) or 0.5n^2 - 0.5*n + 5

05-05-08, 03:54 PM	#10
andy5 iPod Nano 2GB Join Date: Mar 2008 Location: Hertfordshire or sheffield Posts: 172	Re: Maths Question (I call ALL the Geniuses) this isn't how i did it but i believe you can use this formulae a + (n-1)d + 0.5(n-1)(n-2)C Where a is the first term d is the difference between the first term and second term C is the difference increase So in this case... a=5 d= 1 for C 5 6 8 11 15 difference 1 2 3 4 so C=1 then you put the numbers into the equation and simplify this may only work for changing difference formuales... cant really remember

05-05-08, 04:05 PM	#11
the_icks Mr Baldy Chicken Join Date: Mar 2006 Posts: 14,487	Re: Maths Question (I call ALL the Geniuses) . __________________ Last edited by the_icks; 05-05-08 at 04:08 PM..

05-05-08, 04:06 PM	#12
Simmo iPod 30gb Join Date: May 2008 Posts: 1,406	Re: Maths Question (I call ALL the Geniuses) Aye, what they said was right. However, if the difference is the same then you use this formula which is much easier. nth term = dn + (a - d)

05-05-08, 04:07 PM	#13
the_icks Mr Baldy Chicken Join Date: Mar 2006 Posts: 14,487	Re: Maths Question (I call ALL the Geniuses) . __________________

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