Question

The fourth term of an A P Is 4 .Then the sum of first 7 term is​

Answer 1

Answer:

If the fourth term of an A.P. is 4. To find : What is the sum of its first seven terms? Substitute from equation (1), Therefore, the sum of seven terms is 28.

Step-by-step explanation:

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} = n/2 * [2a + (n - 1) * d]

S_{7} = 7/2 * [2a + (7 - 1) * d]

S 7 = 7 2 (2a+6d)

S 7 =7(a+3d)=7*4=28

(·.· of(1))

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