Q.

(log3x2)(log1/2x2)(log4x1)>0 , Then the value of x lies in the interval         

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a

[0,14][4,9]

b

(0,14]

c

(0,14)(4,9)

d

[4,9]

answer is A.

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Detailed Solution

Let S=(log3x2)(log1/2x2)(log4x1)>0

The factor log3x2  becomes  zero at  x=9.
Similarly  the other two factors become zero at  x=1/4  and x=4  . Note that we must consider only positive values of  x.
   We now find the sign scheme of the expression by using some test points inside the       
    various sub-intervals.
We also use the fact that  logax>0  for x>1  if a>1 and  logax>0 for 0<x<1  if  0<a<1 .

Question Image
 

 

 

 

0<x<1/4 Or 4<x<9

x(0,1/4)(4,9)

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(log3x−2)(log1/2x−2)(log4x−1)>0 , Then the value of x lies in the interval