Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • NCERT
  • If tn denotes the nth term of the series 2 + 3 + 6 + 11 + 18 + ... then t50 is A. 492 – 1 B. 492 C. 502 + 1 D. 492 + 2

If t_n denotes the n^{th} term of the series 2 + 3 + 6 + 11 + 18 + ... then t_{50} is

A. 49^2 - 1

B. 49^2

C. 50^2 + 1

D. 49^2 + 2

Answers (1)

S_{n}=2+3+6+11+18+ \ldots +t_{50}(Using method of difference)
       \\ S_{n}=0+2+3+6+11+18+ \ldots +t_{50} \\\\ S_{n}-S_{n}= \left( 2-0 \right) + \left( 3-2 \right) + \left( 6-3 \right) + \left( 11-6 \right) + \left( 18-11 \right) + \ldots -t_{50} \\\\ t_{50}=2+ \left[ 1+3+5+7+ \ldots upto\: \: 49\: \: terms \right] \\\\ t_{50}=2+\frac{49}{2} \left[ 2+ \left( 49-1 \right) 2 \right] \\\\ t_{50}=2+49^{2} \\\\

Hence, correct option is d.

Posted by

infoexpert21

View full answer

Similar Questions

Latest Question