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![[Post New]](/templates/default/images/icon_minipost_new.gif) 11 Jan 2007 20:26:51 IST
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(X to power 1/3) - (X to power 1/9) = 60. find the value of X?
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11 Jan 2007 20:27:58 IST
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(X to power 1/3) - (X to power 1/9) = 60. find the value of X?
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11 Jan 2007 21:46:53 IST
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Let t=x^1/9 (^ means power raised to);
so, the given eq changes to..
t^3 - t =60 ,
i.e; t(t-1)(t+1)=60
=3*4*5 ;
therefore, t=x^1/9=4 ;
hence, x=4^9 .
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12 Jan 2007 12:08:12 IST
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Now that you know t=4 is a solution you can take (t-4) common from t^3-t-60=0 . This will give you an quadratic equation. Solve it to also check for other roots. (You may have three values for t)
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Krishna Gopal Singh
B.Tech Chemical Engg
IIT Delhi 2002
Currently doing PhD from IIT Delhi |
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12 Jan 2007 14:15:52 IST
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The other two values of t r imaginary.
so,if the question was asked for finding for a real value of x,
the solu is ...x=4^9.
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