Question

Find the nth term of these sequences.

1 2 3 4 ...... n
3 6 9 12
​

Answer 1

1st answer is n and 2nd is 3n.

Explanation:

1st one....

first term (a) = 1

common difference (d) = 2-1 =1

no. of term (n) = n

Now,

nth term = a + ( n-1 ) d

= 1 + ( n-1 ) 1

= 1 + n - 1

= n

2nd one...

first term (a) = 3

common difference (d) = 6-3 =3

no. of term (n) = n

Now,

nth term = a + ( n-1 ) d

= 3 + ( n-1 ) 3

= 3 + 3n - 3

= 3n

Answer 2

a=3

d =u2 -u1=6-3=3

un=n/2(2a+(n-1)d)

=n/2 (6+3n+3)

=n/2 (3n+9)

ihope i was help ful