#solution

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tulip coral
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The number of non negative integral solutions of the equation x+y+2z=33

dusk fossilBOT
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tulip coral
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Anyone???

distant nimbus
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general hint

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if you wanna solve x+y=N you have solutions like (0,N), (1,N-1), (2,N-2) etc

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how many are there?

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for x+y+2z = 33, fix a possible value of z and solve x+y = 33-2z as before

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e.g z=0 has you solve x+y=33, z=1 x+y=31 etc

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@tulip coral

tulip coral
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There was a formula can I not apply it here?@distant nimbus

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n+r-1 C r-1

tulip coral
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So i am getting sum

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34+32+30+28+.....0

distant nimbus
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cant have 34

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but you get the idea, so start counting

distant nimbus
tulip coral
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Max z is 16

distant nimbus
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when is this formula true?

tulip coral
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x+y+z=33

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Then it is true i guess

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33+3-1C2

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35C2

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2+4+6+8+....34

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I got 306

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@distant nimbus

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Stop laughing please ๐Ÿ˜ญ๐Ÿ˜‚๐Ÿ˜‚๐Ÿ˜‚๐Ÿ˜‚๐Ÿ˜‚

distant nimbus
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if it is true, then prove it

tulip coral
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What i prove?

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I am telling my answer by your hints

distant nimbus
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the formula you were talking aboutรค

tulip coral
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No formula doesn't work here. It works only for the i guess

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Let me count it and check

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306 is correct?

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@distant nimbus

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Formula works fine here

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Bro see

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@distant nimbus

wanton kestrel
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the coefficient of v^33 in the expansion of 1/[(1-v)^2 (1-v^2)] near 0

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$\underbrace{(v^0+v^1+v^2+\ldots)}{x} \underbrace{(v^0+v^1+v^2+\ldots)}{y}\underbrace{(v^0+v^2+v^4+\ldots)}_{z}$

alpine surgeBOT
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Heavily cooked

tulip coral
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Where did you get the idea?

wanton kestrel
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from the problem

tulip coral
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I saw a same comment on math exchange

wanton kestrel
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gfs are very common in this territory

tulip coral
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gfs?

wanton kestrel
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generating functions

tulip coral
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Girlfriend ๐Ÿ’”๐Ÿ’”

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Ohh lol

wanton kestrel
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The number of non negative integer solutions to ax_1 + bx_2 + cx_3 +... = n where a, b, c,... are integers is the coefficient of x^n in 1/[(1-x^a)(1-x^b)(1-x^c)...]

tulip coral
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Yes bro

wanton kestrel
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if a_1, a_2,...,a_k are coprime then the number of solutions to a_1 x_1 +...+ a_k x_k = n is ~ k^n/[(n-1)!a_1 a_2...a_k]

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it helps if n is huge

tulip coral
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+close