Question

20th term of an AS 60 and 40th term 140. a)d=?.50th term?nth term?​

Answer 1

Answer:

given

a20=60

a40=140

a20=a+19d=60---(1)

a40=a+39d=140---(2)

(2)-(1)

a+39d=140

a+19d=60

----------------(substract)

20d=80

d=4

60=a+19(4)=> a=60-78=-18

now , a50=a+49d

= -18+49(4)

an=a+(n-1)d