Login/Sign Up
Home » 2.(i) Which term of the AP …. is
2.(i) Which term of the AP 3,8,13, …. is 248?
Arithmetic Progression | Class 10 | ICSE | Maths | RD Sharma
2.(i) Which term of the AP 3,8,13, …. is 248?

(ii) Which term of the AP 84,80,76, … is 0?

An arithmetic progression or arithmetic sequence is a number’s sequence such that the difference between the consecutive terms is constant.

Solution:

(i) Given A.P. is 3,8,13, ………..

First term \left( a \right)=3

Common difference \left( d \right)= Second term – first term

=8-3

=5

We know that, {{n}^{th}} term \left( {{a}_{n}} \right)=a+\left( n-1 \right)d

And, given {{n}^{th}} term {{a}_{n}}=248

248=3+\left( n-1 \right)5

248=-2+5n

5n=250

n=250/5=50

\therefore {{50}^{th}} term in the A.P is 248.

(ii) Given A. P is 84,80,76, …………

First term \left( a \right)=84

Common difference \left( d \right)={{a}_{2}}-a

=80-84

=-4

We know that, {{n}^{th}} term \left( {{a}_{n}} \right)=a+\left( n-1 \right)d

And, given nth term is 0

0=84+\left( n-1 \right)-4

84=+4\left( n-1 \right)

n-1=84/4=21

n=21+1=22

\therefore {{22}^{nd}} term in the A.P is 0.

i

More Material