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29 Dec 2007 19:03:27 IST

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299

plz solve this

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if log_e(1+x)=^{_x/1-x2_/2+x3_/3-x4_{/4.................................}}

terms

1.the coefficient of x²³ in the expansion of log^_e(1+x/1-x)

^{2.the coefficient of x^21 in the expansion of log_e(1+x+x^2)}

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Comments (3)

Pratik Anand

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Joined: 11 Jun 2007

Posts: 914

29 Dec 2007 19:53:31 IST

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IS IT 2/23??

by using property of log , it is converted to

log(1+x) - log(1-x)

so expand it and as coefficient of x^23 (i.e. 1/23) in second log is -ve so it turns to +ve and added up.

rate if satisfied......

dont u know me

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Joined: 5 Dec 2007

Posts: 704

29 Dec 2007 23:30:56 IST

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hellllo pratik !!!!!!!!!!!!!!!!!!!!! yaar 23 is not an even no its actually an odd no so d coeff must be zeeeeeeeeeeeero

Pratik Anand

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Joined: 11 Jun 2007

Posts: 914

29 Dec 2007 23:35:42 IST

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see the expansion above............... even ones are getting -ve. so in case of log(1-x), odd ones will be getting -ve. but as it is subtracted then -ve and -ve makes a +ve . so it will add up to 1/23 of log (1+x)

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