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Cant get this math.
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John Anderton
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RE: Cant get this math.
Programing languages (and the Svip, more importantly ;)) agree.
Our hypothesis of zeroness must be correct! :o
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04-28-2008 05:35 PM
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somelauw
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RE: Cant get this math.
I solved them too by taking the formulas I know and then adjusting them to the ones similair by your sequences:
code:
1,3,6,10
y = (number/2) * (first + last)
y = (x/2)(x+1) = (x*x +x)/2

3, 6, 10, 15, 21
y = (x+1)(x+2)/2 = (x*x + 3x + 2)/2


1,2,4,8
y = g ** x
y = 2 ** (x - 1)

8, 16, 32, 64, 128
y = 2 ** (x + 2)

Edit: I assumed y(1) is the first value in both sequences.
Edit2: Power/multiplication typo. I prefer ** for powers.

This post was edited on 04-28-2008 at 06:20 PM by somelauw.
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04-28-2008 05:43 PM
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John Anderton
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RE: Cant get this math.
quote:
Originally posted by somelauw
I solved them too by taking the formulas I know and then adjusting them to the ones similair by your sequences:
code:
1,3,6,10
y = (number/2) * (first + last)
y = (x/2)(x+1) = (x*x +x)/2

3, 6, 10, 15, 21
y = (x+1)(x+2)/2 = (x*x + 3x + 2)/2


1,2,4,8
y = g * x
y = 2 * (x - 1)

8, 16, 32, 64, 128
y = 2 * (x + 2)


Firstly, refer to my post earlier in this thread.
Secondly, expression 1 is wrong. I mean the pattern you've considered isn't the one he wants...
The first expression is correct since its a standard. Its usually written as x*(x+1)/2 :-)
In the second expression, you are missing the condition where the first value (initial value) is to be taken as x=0; Your expression would be correct if you would have considered that. :-) (read my post for a complete explanation)
Third expression is horribly wrong. You've mixed up multiplication and exponentiation :P
Fourth expression is wrong because the series is the power of 2 series. You're multiplying 2 with numbers like 3,4,5,6 which won't give you the answers. What you needed was the raised to (also called exponential; noted as ^) and not the multiplication sign. If you replace the multiplication by exponentiation and consider the zero criteria (as mentioned in my post, your answer would be correct)
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04-28-2008 05:57 PM
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somelauw
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RE: Cant get this math.
JA, you're right. I corrected my mistakes.
I didn't remember whether 0 or 1 should be taken as first number for x. I though that both where acceptable.
For powering I prefer the ** sign, because ^ could also stand for bitwise xor. I only made a slight typo by forgetting to double the *.

This post was edited on 04-28-2008 at 06:25 PM by somelauw.
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04-28-2008 06:24 PM
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John Anderton
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RE: Cant get this math.
quote:
Originally posted by somelauw
For powering I prefer the ** sign, because ^ could also stand for bitwise xor. I only made a slight typo by forgetting to double the *.
yeah, ^ is bitwise ex-or but that's in programming, something we're not referring to now. ** would have worked too :P
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04-28-2008 06:26 PM
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Pr0xY
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RE: RE: Cant get this math.
quote:
Originally posted by Phillip
quote:
Originally posted by Bilbo
There are two patterns that I couldn't figure out, and nither could my teacher when I asked her.

Wow your math teacher must be kinda stupid =\

Well it is Canada.


.. J/k!!

This post was edited on 04-28-2008 at 07:22 PM by Pr0xY.
04-28-2008 07:21 PM
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foaly
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RE: Cant get this math.
quote:
Originally posted by John Anderton
They start with n=0, fool (Smilie)
He said, initial value is 3. Implies for n=0, value=3; Then next value is 6 implies for n=1, value=6.
quote:
Originally posted by Bilbo
Pattern: 8, 13, 18, 23, 18, 33
Description: Start at 8 then add 5.
Expression: n5+3
1*5+3 =8

and my name is foaly not fool :(
04-28-2008 08:16 PM
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markee
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RE: Cant get this math.
quote:
Originally posted by John Anderton
Programing languages (and the Svip, more importantly ;)) agree.
Our hypothesis of zeroness must be correct! :o
Well except if you deal with maths programs like matlab, then it starts from 1, but that is becausethey store every variable in a matrix (2 dimensional array)
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04-28-2008 08:51 PM
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