what is 87th term in the given series:
2,10,26,50

• Observing the given we can write the following :
  
  
  2nd term - 1st term = 1*8;
  3rd term - 2nd term = 2*8;
  4th term - 3rd term = 3*8;
  5th term - 4th term = 4*8;
  .
  .
  .
  (n-1)th term - (n-2)th term =(n-2)*8
  (n)th term - (n-1)th term =(n-1)*8;
  ---------------------------------------------
  Summing up all the above terms we get ,
  (n)th term - 1st term = {1+2+......+(n-1)}*8
  =>(n)th term = 8*{n*(n-1)}/2 + 1st term
  =>(n)th term = 8*{n*(n-1)}/2 +2;
  So, Clearly 87th term of the sequence will be :
  8*{n*(n-1)}/2 +2 = 8*{87*86}/2 +2 = 4*86*87 +2 = 29930
  
  Hence, 87th term will be : 29930
• 12 years agoHelpfull: Yes(9) No(0)
• its general term will be (2n-1)^2 + 1 ...put n= 87...so ans will be 299230
• 12 years agoHelpfull: Yes(2) No(0)
• series is increasing as 2, 2+8*1 ,2+8*1+8*2 , 2+8*1+8*2+8*3,....up to n..
  so 87 th term will be as
  2+8*1+8*2+8*3+....+8*86
  =2+8(1+2+3+4+...+86)
  =2+8*(86*87/2)
  =2+29928
  =29930 ans.
  
• 12 years agoHelpfull: Yes(2) No(0)