SOLUTION: In the expansion of (1 + 1/6x) to the power n, n belongs to N, n>8 the coeffient of x to the power 7 and x to the power 8 are equal find n. I have tried n(n-1)....(n-6) (1) to t

Algebra ->  Sequences-and-series -> SOLUTION: In the expansion of (1 + 1/6x) to the power n, n belongs to N, n>8 the coeffient of x to the power 7 and x to the power 8 are equal find n. I have tried n(n-1)....(n-6) (1) to t      Log On


   



Question 328502: In the expansion of (1 + 1/6x) to the power n, n belongs to N, n>8 the coeffient of x to the power 7 and x to the power 8 are equal find n.
I have tried n(n-1)....(n-6) (1) to the power n-7 all over 7!
and n(n-1)....(n-7)(1) to the power n-8 all over 8!
1 = n-7 over 8
8 = n-7
n=15

Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Are you forgetting the (1%2F6)?
I used k instead of n so I didn't confuse with N.
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%28matrix%282%2C1%2Cn%2Ck%29%29=%28matrix%282%2C1%2Cn%2Ck%2B1%29%29%2A%281%2F6%29
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Start there, that should get you in the right direction.