Why was this wrong?

[strong bolt]

I applied stars and bars after subtracting 10 from 17. I got C(7+3,3) = 120 but its wrong. Could anybody see what I did wrong?

[tepid heart]

1. Ask your question and show the work you've done so far. If you've posted a screenshot of a question, specify which part you need help with.
2. Wait patiently for a helper to come along.
3. Once someone helps you, say thank you and close the thread with:

   +close
   

4. Feel free to nominate the person for helper of the week in #helper-nominations
5. Do not ping the mods, unless someone is breaking the rules.
6. If you're happy with the help you got here, and the server overall, you can contribute financially as well:

[slender robin]

i mean it says x_i belongs to Natural numbers
so it has to be greater than or equal to 1 for all x_i

shouldn't we take that to account?

[strong bolt]

I tried that in the first part but C(20,3) was the right answer so I think 0 is included in this version of natural numbers

[slender robin]

yeah
cause in that case it would be 560 for first part

[strong bolt]

yea tbh it might be just a autograding error but i want to make sure

[slender robin]

i mean i dont see a mistake
x1 + x2 + x3 + x4 = 7

then bijection must be C(10,7)

[strong bolt]

alr thanks

[slender robin]

try putting 12 as answer? if you can

[strong bolt]

ok

12 didjnt work it told me the answer was 286

idk how

C(13,3)

[slender robin]

yeah i dont get

the question must be wrong !!
first it says natural numbers then it uses 0 as solution as well
then ignoring that
120 must be correct idk

[strong bolt]

yea imma go ask the professor later

thanks tho

[slender robin]

aight !

[strong bolt]

+close