lawls
Find the 7th term of (x^2 + 3y)^9



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amistre64
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looks like a pascal

amistre64
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given: \[(p+q)^n\]
we can work out the middle stuff as:\[p^{nc}q^c\]
the coeeficient is a little tricker unless you know about combinatorics

amistre64
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and c is the "term" value :)

amistre64
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n choose c is what i think i recall for the coeff; or else draw up the pascal triangle

shubhamsrg
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dw:1358788894374:dw
This is the working formula.

amistre64
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that looks about right, but if i remember it correctly: the first term starts at 9 and drops down till it hits the 7th term

shubhamsrg
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Didn't get you ?

shubhamsrg
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The first term's coefficient is 1 , when r=0,

amistre64
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(a+b)^9
a^9 a^8 a^7 a^6 a^5 a^4 a^3
^^^
b^0 b^1 b^2 .... b^6
^^^
these always get turned around in my head

lawls
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ok thanks

amistre64
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good luck ;)