Shoutbox

I have to write expressions for patterns.
example:
Pattern: 8, 13, 18, 23, 18, 33
Description: Start at 8 then add 5.
Expression: n5+3

There are two patterns that I couldn't figure out, and nither could my teacher when I asked her.

1.
Pattern: 3, 6, 10, 15, 21
Description: Start at 3, then add 3, next add 4 and so on and so forth.
Expression: ???

2.
Pattern: 8, 16, 32, 64, 128
Description: Start at 8, then multiply by 2.
Expression: ???

Please help.

1) Start at 3; Add 3, then 4 then 5...
q=p+(3+n)
Where q = current answer (ie nth value)
and p = previous answer (ie (n-1)th value)
Initialise n=0 and p=3

4) Indices of 2 starting from 8
q=p*2
Initialise p = 8
Or, q=2^(n+3)

quote:

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Originally posted by Bilbo
8, 16, 32, 64, 182

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More like 128

quote:

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Originally posted by Bilbo
There are two patterns that I couldn't figure out, and nither could my teacher when I asked her.

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Wow your math teacher must be kinda stupid =\

quote:

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Originally posted by Phillip

quote:

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Originally posted by Bilbo
There are two patterns that I couldn't figure out, and nither could my teacher when I asked her.

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Wow your math teacher must be kinda stupid =\

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incredibly, if the teacher doesnt understand it, then why is she giving them these questions without knowing how to do it first?

I'm still in grade 8, it's not like all the teacher does is math. In fact, she does everything but french.

EDIT:
JA: You're supposed to be able to do it with only n, without knowing the previous number.

quote:

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Originally posted by Bilbo
I'm still in grade 8, it's not like all the teacher does is math. In fact, she does everything but french.

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you rock, but the teacher should know how to do the equations...

also, JA.

quote:

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Originally posted by JA
q=2^(n+3)

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it's q=2^(n+2)

1)  p = (n+2)(n/2+1.5)

I realise it isn't the easiest to find, but it shouldn't take a maths teacher more than 5min... And where was the class nerd to anser this one?

quote:

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Originally posted by markee
1)  p = (n+2)(n/2+1.5)

I realise it isn't the easiest to find, but it shouldn't take a maths teacher more than 5min... And where was the class nerd to anser this one?

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Thanks, and just ftw I am the class nerd.

Also, like I said before she doesn't do just math, she teaches all our subjects.

markee: using yours, if n=4 then p=21. It should = 23.

quote:

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Originally posted by markee
p = (n+2)(n/2+1.5)

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eh ?

much easier:

n(n+1)
   2

for n=1,2,3...

The sequence begins with 1, i.e. 1, 3, 6, 10, 15, 21, 28 etc.

(Triangular numbers btw.)