Question

Find some of first 16 terms of AP 10 , 6, 2 .........

Answer 1

Answer:

320

Step-by-step explanation:

actually the answer is -320....but in an AP the sum of any terms cannot be minus

Answer 2

Answer:

Note:

If an AP has a as its first term and d as common difference, then the sum of its n terms is given by ;

S(n) = (n/2)•{2a + (n-1)d}

Here, the given AP is : 10 , 6 , 2 ,......

Clearly, we have;

a = 10

d = 6 - 10 = - 4

n = 16 ( given)

Now, putting these values in the formula,

we get;

=> S(n) = (n/2)•{2a + (n-1)d}

=> S(16) = (16/2)•{ 2•10 + (16 - 1)(- 4) }

=> S(16) = 8•{ 20 + 15(- 4) }

=> S(16) = 8•{ 20 - 60 }

=> S(16) = 8•(- 40)

=> S(16) = -320

Thus, the required sum is :

– 320.