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Exponentiate Negatively, Get Value (Posted on 2007-12-24) Difficulty: 2 of 5
Given that:
     y
   (g(p))-2 dp = g(y), 
    0
and:
     4
   (g(p))-2 dp = (12)1/3.
    0
Find the value of g(72)

  Submitted by K Sengupta    
Rating: 3.0000 (1 votes)
Solution: (Hide)
g(72) = 6

EXPLANATION:

Differentiating both sides of the first relationship with respect to y, we obtain:

g’(y) = (g(y))-2, so that:
(g(y))2*g’(y) = 1

Integrating both sides w.r.t y, we obtain:

(g(y))3/3 = y+c
Or, (g(y))3 = 3(y+c)……..(*)

From the first relationship, we also note that:
g(0) = 0, so that, (*) gives:
(g(0))3 = 3c, so that:
c=0

Accordingly, (g(y))3 = 3y, so that:
(g(72))3 = 3*72=216
or, g(72)= 6

*** I am grateful to Chesca Ciprian, who has rightly pointed out that the second condition of the problem is superfluous.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re: Observation..........K Sengupta2008-03-06 04:35:54
re: Observation..........Kurious2007-12-26 08:05:19
Some ThoughtsObservation..........Chesca Ciprian2007-12-25 12:49:56
re(2): complete solutionDaniel2007-12-25 10:52:58
Solutionre: complete solutionKurious2007-12-25 10:12:40
complete solutionDaniel2007-12-25 02:14:37
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