Q.

The 8th common term of the series

S1=3+7+11+15+19+...,

S2=1+6+11+16+21+.... .

is _________ .                       [2023]


Ans.

(151)

S1=3+7+11+15+19+

a1=3,  d1=4

S2=1+6+11+16+21+

a2=1,  d2=5

First common term, a = 11

Common difference, d=LCM(d1,d2)=LCM(4,5)=20

8th common term of the series

      a8=a+7d=11+7×20=151