the sum of series represented as
1/(1*5) + 1/(5*9) + 1/(9*13) +..... + 1/(221*225) is
option
a)28/221
b)56/221
c)56/225
d)none of these

• 1/(1*5) + 1/(5*9) + 1/(9*13) +..... + 1/(221*225)
  =(1/4)*[(5-1)/(1*5) + (9-5)/(5*9) + (13-9)/(9*13) +..... + (225-221)/(221*225)]
  =(1/4)*[(1- 1/5)+(1/5 - 1/9)+(1/9 -1/13)+...(1/221 -1/225)]
  =(1/4)*(1- 1/225)
  =(1/4)*(224/225)
  =56/225
  
  c)56/225
• 10 years agoHelpfull: Yes(225) No(2)
• Brilliant Rajesh.rakesh jindabad
  
  
• 10 years agoHelpfull: Yes(21) No(2)
• 1/4*[(1-1/5)+(1/5-1/9)+(1/9-1/13)........+(1/221-1/225)]
  1/4*[1-1/225]
  1/4*[224/225]
  answer is 56/225
• 10 years agoHelpfull: Yes(3) No(1)
• 1/(1*5) + 1/(5*9) + 1/(9*13) +..... + 1/(221*225)
  =(1/4)*[(5-1)/(1*5) + (9-5)/(5*9) + (13-9)/(9*13) +..... + (225-221)/(221*225)]
  =(1/4)*[(1- 1/5)+(1/5 - 1/9)+(1/9 -1/13)+...(1/221 -1/225)]
  =(1/4)*(1- 1/225)
  =(1/4)*(224/225)
  =56/225
  
  56/225
  
• 10 years agoHelpfull: Yes(3) No(0)
• jiyo rakesh
• 9 years agoHelpfull: Yes(1) No(0)
• c
  find the approx value
• 10 years agoHelpfull: Yes(0) No(0)
• Rakesh babua jindabad...
• 9 years agoHelpfull: Yes(0) No(0)
• 1/4*1[1/1-1/225] short cut method
• 9 years agoHelpfull: Yes(0) No(2)