Question

the 2nd and the 5th terms of a gp are -1/2 and 1/16 respectively find the sum of first 8 terms

Answer 1

Answer:

Step-by-step explanation:

We know that a+d = -1/2 and a+4d = 1/16

By subtracting the second term from the 5th term, we get

a+4d - (a+d) = 1/16 -(-1/2)

3d = 1/16 + 8/16

3d = 9/16

d = 3/16

SInce a+d = -8/16,

a+3/16 = -8/16

a = -11/16

Now, we know that:

a = -11/16

d = 3/16

And the given condition, n = 8.

Summation of an A.P = n/2{2a + (n-1)d}

8/2{-22/16 + (8-1)3/16}

4(-22/16 + 21/16)

4(-1/16)

-4/16

= -4

Therefore, the sum of the first 8 terms of the A.P is -4.

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