what will be the 9th & 99th number of the following series:
2, 10, 26, 50........................

• if we observe pattern
  2nd number is (8*1)+2
  3rd number is (8*2)+(8*1)+2
  4th number is (8*3)+(8*2)+(8*1)+2
  hence 9th number is (8*8)+(8*7)+...+(8*2)+(8*1)+2
  =8(8+7+6+5+4+3+2+1)+2
  =8((8*9)/2)+2 (sum of n numbers)
  =288+2
  =290
  99th number is (8*98)+(8*97)+(8*96)+...+(8*2)+(8*1)+2
  =8(98+97+96+...+2+1)+2
  =8((98*97)/2)+2
  =38808+2
  =38810
  9th number is 290 & 99th number is 38810
• 10 years agoHelpfull: Yes(36) No(4)
• This is in the form
  1^2+1,,3 ^2,,5^2+1,,7^2+1
  so 9th number will be 17^2+1
  and 99th number is =197^2+1
• 10 years agoHelpfull: Yes(19) No(0)
• Is form a quadratic eqn ax^2 +bx + c =tn
  Implies a+b+c=2
  4a+2b+c=10
  9a+3b+c=26
  Solving u get a 4 b -4 and c 2
  Eqn bcm 4x^2-4x+2
  Put x 9 for ninth term .it will be 290
• 10 years agoHelpfull: Yes(1) No(1)
• 290 for 9th term
  i.e
  9*2=18-1=17=17*17+1=289+1=290
  now
  99*2=198-1=197
  197*197+1
  
• 10 years agoHelpfull: Yes(0) No(0)
• t9=2+(9-1)*8=66
  t99=2+(99-1)*8=786
• 4 years agoHelpfull: Yes(0) No(0)