Question

Fourth term of an arithmetic progression is 8. What is the sum of the first 7 terms of thearithmetic progression?

Answer 1

Answer:

Step-by-step explanation:

a + 3d = 8.

a + a + d + a + 2d + a + 3d + a + 4d +

+ a + 5d + a + 6d = 7a + 21d

= 7(a + 3d) = 7×8 = 56.

Answer 2

Answer: Sum of first 7 terms of A.P. would be 56.

Step-by-step explanation:

Since we have given that

Fourth term of A.P. = 8

As we know the formula for A.P.:

$a+(4-1)d=8\\\\a+3d=8$

We need to find the sum of first 7 terms of the arithmetic progression:

$S_7=\dfrac{7}{2}(2a+(7-1)d)\\\\S_7=\dfrac{7}{2}(2a+6d)\\\\S_7=3.5\times 2(a+3d)\\\\S_7=3.5\times 2\times 8\\\\S_7=56$

Hence, Sum of first 7 terms of A.P. would be 56.