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Find the value of ...... (Posted on 2006-05-14) Difficulty: 3 of 5
If a + b + c = 0, then find the value of

[(bc)/a + (ca)/b + (ab)/c].[a/(bc) + b/(ca) + c/(ab)]

No Solution Yet Submitted by Ravi Raja    
Rating: 4.0000 (1 votes)

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Solution re(2): Solution_ An Alternate Solution To The Puzzle | Comment 5 of 6 |
(In reply to re: Solution by Richard)

My opinion is in conformity with the observations made by Richard. I do not believe that it would be feasible for me to match Bractal's formatting. <o:p></o:p>

An alternate solution to the puzzle is provided below:<o:p> </o:p>

  1. Denoting  the given expression as S*T; where S = (b c)/a + (c a)/b + (a b)/c; and T = a/(b c) + b/(c a) + c/(a b); we obtain S = -(a-b)(b-c)(c-a)/(abc), upon simplification.<o:p></o:p>
  2. Substituting, p = a-b; q = b-c and r = c-a, we observe that p-q = a-2b+c = -3b ( since a+b+c =0).
    Similarly, q-r = -3c and r-p = -3a, so that:T = - (1/3)*[(r-p)/ q +(p-q)/r + (q-r)/p]
    = -(1/3)[(p-q)(q-r)(r-p)/(pqr)]
    = -(1/3)[(-3b)(-3c)(-3a)][1/(a-b)(b-c)(c-a)]
    = (9abc)/ [(a-b)(b-c)(c-a)]
    = 9/S; so that ST = 9, which is the required value of the given expression.

<o:p> </o:p>


  Posted by K Sengupta on 2006-05-14 23:03:20
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