87th no. of series 2,10,26,50....

• sum= 2+10+26+50 upto 87 terms
  sum= 2+10+26 86th +87th trm
  (by sub) 0=2+[8+16+24+ upto 86 terms]-87th trm
  so 87th trm=2+8[1+2+......+86]
  =2+8*86*87/2
  =2+29928=29930
• 12 years agoHelpfull: Yes(20) No(1)
• answer is =29930
  series is 2,10,26,50
  like 1st term is 2 = 1^2+1
  2nd term is 10= 3^2+1
  3rd term is 26= 5^2+1
  similarly 87 term is = 173^2+1=29930......
  as we seen above that in 1st ,2nd,& 3rd term it is squire of corresponding odd numbers+1
  since 1st odd no is 1(1*2-1),,,,,2nd odd no is 3 (2*2-1),,,,3rd odd no is 5(2*3-1).....similarly 87 odd no is (2*87-1)= 173......
• 12 years agoHelpfull: Yes(20) No(1)
• 29930....
  1 st term = 2
  2nd term = 2+8(1)
  3rd term = 2+8(1)+8(2)
  .
  .
  87 th term =2+8(1)+8(2)+....8(86)
• 12 years agoHelpfull: Yes(9) No(0)
• Ans:29930
  1 st term = 2
  2nd term = 2+8*1
  3rd term = 2+8*1+8*2
  .
  .
  87 th term =2+8*1+8*2+....8*86
  = 2+8*86*87/2
  =29930
  
• 12 years agoHelpfull: Yes(6) No(0)
• 26570
  
  1^2+1
  3^2+1
  5^2+1
  7^2+1
  .
  .
  .
  .
  163^2+1
• 12 years agoHelpfull: Yes(2) No(3)
• 10-2=8
  26-10=16
  50-26=24
  x-50=32
  so tha ans is (50+32)=82
• 12 years agoHelpfull: Yes(0) No(3)