maths

[sirkillalot617]

well im a bit stuck on my course work can anyone help

sequence 10,40,90,160,250,360
First difference30,50,70,90,110
second difference20,20,20,20

now i need to find a formular for it i know as the second difference is the same it has a n2 and the coefficient of n2=20 divided by 2
=10 so it has 10n2 now im stuck

[Slug Toy]

well i think the answer may be staring right at you. it looks like its going by increasing odd numbers times ten.

the differences:

30=3x10
50=5x10
70=7x10
90=9x10
110=11x10

3, 5, 7, 9, 11, and so on, and you just need to multiply them by ten. i think you were trying too hard to find a clever solution, when a fairly simple one was right there.

[sirkillalot617]

im afraid i know the answer is 10(n-1)2 just need to know how i get there

[Slug Toy]

that doesnt really make sense though. an equation involving (n-1) wouldnt get you nice round numbers like 10, 40, 90, 160 in that smooth of an increasing order. if you have 10(n-1)2 the sequence would look like 10, 180, 3580.. and it jumps up really fast. i just cant see how an (n-1) fits in there.

[Zephik]

Your all wrong. The answer is 42.

Sorry, I couldn't resist.

**Just in case nobody got that, I was referring to The Hitch Hikers Guide to the Galaxy. Just thought I would mention that because when I came back and read my post, It took me like 5 whole seconds to remember what I was thinking about when I posted. haha, thats so sad... ><

[silverdemon]

n: 1 2 3 4 5 6 7
x: 0 10 40 90 160 250 360

this looks allright to me slug, only this sequence starts with 0 and the sequence mentioned in the first post starts with 10... so if the sequence would start with 10 then it should be 10*n^2 if you ask me...

how to get there? well I think it is just a matter of seeing the solution. If you see that 1, 4, 9, 16, 25... are squares than you should be able to make the formula for the sequence...

hope that helps

[Slug Toy]

ok, i see the squares. kind of funny... i saw that pattern popping up when i was fiddling with those coded messages for a while. i saw the squares popping up, and the difference between the values being increasing multiples of odd numbers. i should have seen that right away here.

[sirkillalot617]

thanks silver demon now i get what my teacher was on about the answers are all out off line becuse 10 is surposed to be at one cheers plus rep for helping

[armadilloben]

what grade math do u take dude im confused to much algebra!!! i was thinkin it was like X3 - 20 or sumtin but i got confused

[isunktheship]

This isn't anything too special, it's like 2nd year High School math. I would assume that by the title of the thread "Maths" that you are a British student. I love this type of stuff.

Also, when you are trying to express powers you use the carrot, '^'.

In this case the pattern is
10*(n-1)^2
If you recall order of operations...
in this situation we take the '(n-1)'
then square it with '^2'.
After that you just multiply it by ten, '10*'

Good stuff! ...and good luck in math!

[jdbnsn]

Your all wrong. The answer is 42.

Sorry, I couldn't resist.

**Just in case nobody got that, I was referring to The Hitch Hikers Guide to the Galaxy. Just thought I would mention that because when I came back and read my post, It took me like 5 whole seconds to remember what I was thinking about when I posted. haha, thats so sad... ]

Totally thought that's what you meant! Wasn't that the computed answer to the question "What is the meaning of life?"