Question

4th term are in A.P. the sum of the 3rd term and 4th term is 2 less than 3 times the sum
term and 2nd term. If its 4th terms is 18. Find the 4 terms of the A.P.
​

Answer 1

Step-by-step explanation:

Let a,d and a

n

be the first term,common difference and n

th

term of given AP.

Given, a

4

=3a

⇒a+3d=3a

⇒2a=3d

⇒a=

2

3d

......(1)

a

7

=2a

3

+1 (given)

⇒a+6d=2(a+2d)+1

⇒a+6d=2a+4d+1

⇒a−2d=−1 .......(2)

Substitute a =

2

3d

in equation (2)

2

3d

−2d=−1

⇒−d=−2

and a =

2

3d

= 3

So, first term is 3 and common difference is 2