log 2,log(2x-1),log(2x+3) are in ap then value of x is?
a)log 5 base 2 b)1/2 c)not remmember d)log 2 base 5

• Q. is absolutely right...
  here is sol url---> http://postimg.org/image/442gpmi9l/
• 9 years agoHelpfull: Yes(22) No(0)
• Ans---5/2
  In exam one was log 32 base 4 i.e 5/2
• 9 years agoHelpfull: Yes(8) No(0)
• I think Q is incorrect (2x nahi 2^x hoga)
  If log 2 , log (2^x-1) , log ( 2^x+3) are in A.P
  2 log (2^x-1)= log 2 + log (2^x+3)
  log (2^x-1)^2 = log {2(2^x+3)} using this property ( log m + log n = log m/n)
  cancel log both sides & let 2^x=y
  (y-1)^2 = 2(y+3)
  y^2+1-2y=2y+6
  y^2-4y-5=0
  y^2-5y+y-5=0
  y(y-5)+1(y-5)=0
  y=5 or y= -1
  2^x=5 (2^x not equal to -1)
  x= log 5 base 2 ( option a)
  
  another sol. if Q is correct
  acc. to Q
  2log(2x-1)= log 2+ log (2x+3)
  (2x-1)^2= 2(2x+3)
  4x^2+1-4x=4x+6
  4x^2-8x-5=0
  4x^2-10x+2x-5
  2x(2x-5)+1(2x-5)
  (2x-5)(2x+1)
  x=5/2 ( x not equal to -1/2)
  
  
• 9 years agoHelpfull: Yes(4) No(4)
• @ Mamta i hv alrdy mention the sol url in the Q...
• 9 years agoHelpfull: Yes(1) No(0)
• plzz guys help me .I got confused .question is how many 5 digits can be formed by using 0,2,4,6,8 which is divisible by 8...i solved and i got answer 20.but this is not in option.,
  the last 3 digit must be divisible by 8 so 024 can be arrannge in 2 ways only 024 and 240.but in others solution I saw they mentioned it arrange in 6 ways .I dont know how ..Plz make me understand yarr.If anone Know the correct method to solve it
• 9 years agoHelpfull: Yes(0) No(1)
• @Mamta mam....
  1*2*3.....
  3(240,248,024)
  2(2 digit left)
  1 digit left
• 8 years agoHelpfull: Yes(0) No(1)
• @Mamta mam....
  1*2*3.....
  3(240,248,024)
  2(2 digit left)
  1 digit left
• 8 years agoHelpfull: Yes(0) No(1)