BITSAT2009MathematicsStraight LinesActual
The (100^ th ) term of the sequence (1,2,2,3,3,3,4,4 ), (4,4, ) is
Options
- A12
- B13
- C14
- D15
Correct answer
C. 14
Step-by-step solution
( aligned & 1^ st term 1,2^ nd term =2,4^ th term 3, & 7^ th term 4,11^ th term 5, aligned ) Series is (1,2,4,7,11, ) (a_n=1+ n(n-1) 2 = n^2-n+2 2 ) If (n=14 ), then (a_n=92, If n=15 ), then (a_n=106 ).