Find the Product of the terms of a sequence

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Moon
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Find the Product of the terms of a sequence

Unread post by Moon » Thu Jan 06, 2011 7:35 pm

Let $x_1=97,x_2=\frac{2} {x_1},x_3=\frac{3} {x_2},x_4=\frac{4} {x_3},\cdots,x_8=\frac{8} {x_7}$
\[ x_1x_2\cdots x_8=?\]
AIME 85/1
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AntiviruShahriar
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Re: Find the Product of the terms of a sequence

Unread post by AntiviruShahriar » Thu Jan 06, 2011 8:16 pm

$x_1 \cdot \frac{2}{x_1} \cdot x_3 \cdot \frac{4}{x_3} \cdot x_5 \frac{6}{x_5} \cdot x_7 \frac{8}{x_7}=2 \cdot 4 \cdot 6 \cdot 8=384$
:mrgreen:

Dipan
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Re: Find the Product of the terms of a sequence

Unread post by Dipan » Thu Jan 06, 2011 9:56 pm

Mine is also 384....

X1 = 97 , X2=97/2 ,X3=291/3 ,X4=12/291 ,X5=1455/12 ,X6=72/1455 ,X7=10185/72 ,X8 = 576/10185
SO,.........................= 97.2/97.291/3.12/291.1455/12.72/1455.10185/72.576/10185
SO,.........................=384

kamrul2010
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Re: Find the Product of the terms of a sequence

Unread post by kamrul2010 » Thu Jan 06, 2011 10:06 pm

AIME ই তে কিছু সমস্যা দেয় যেগুলা দেখলে মনে আশা জাগে!

IMO দেখলে কাঁপাকাঁপি শুরু হয়া যায়! :(
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tushar7
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Re: Find the Product of the terms of a sequence

Unread post by tushar7 » Fri Jan 07, 2011 2:07 pm

1st couple of questions of AIME is pretty doable ,but last 2-3 problems are much more harder

abir91
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Re: Find the Product of the terms of a sequence

Unread post by abir91 » Fri Jan 07, 2011 6:24 pm

kamrul2010 wrote:AIME ই তে কিছু সমস্যা দেয় যেগুলা দেখলে মনে আশা জাগে!

IMO দেখলে কাঁপাকাঁপি শুরু হয়া যায়! :(
আরে কি কস, আই এম ও আমাদের দেখে কাপে। :twisted:
Abir

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Re: Find the Product of the terms of a sequence

Unread post by sourav das » Wed Jan 26, 2011 1:54 pm

I think it has a better solution.\[x_{1}x_{2}=2;x_{3}x_{4}=4....

\therefore x_{1}x_{2}...x_{8}=2*4*6*8=384
\]
Am i right? :)
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