n is positive integer
the 3rd term coeff. = 9375
find n
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binomial.
2011-04-10 5:30 am
(5+x^2)^n , ascending powers of x
n is positive integer
the 3rd term coeff. = 9375
find n
n is positive integer
the 3rd term coeff. = 9375
find n
回答 (1)
2011-04-10 8:30 am
✔ 最佳答案
首先9375 = 3 * 5^5。其次因第三項的係數是9375。故得C(n,2) * 5^(n-2) = 3* 5^5
[n(n - 1)/2] * 5^(n-2) = 3* 5^5
兩相比較即得n = 6。
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110409000051KK01186