Question

If the 4th term of an A.P. is 4 and the common difference is 6. Find the sum of first 16 terms.​

Answer 1

Answer:

Answer

Correct option is

B

28

Let a and d be the first term and common difference of A.P. Then,

a

4

=4⇒a+3d=4 ...(1)

Now, S

n

=

2

n

[2a+(n−1)d]

∴S

7

=

2

7

[2a+(7−1)d]

⇒S

7

=

2

7

(2a+6d)

⇒S

7

=7(a+3d)=7×4=28 ( ∵of(1))

Therefore option B is correct

Answer 2

Answer:

Let a and d be the first term and common difference of A.P. Then,

a

4

=4⇒a+3d=4 ...(1)

Now, S

n

=

2

n

[2a+(n−1)d]

∴S

7

=

2

7

[2a+(7−1)d]

⇒S

7

=

2

7

(2a+6d)

⇒S

7

=7(a+3d)=7×4=28 ( ∵of(1))

I hope it is helpful for you