Question

The sum of first 16 terms of the AP: 10, 6, 2, ... is ______.

 

Options

• 320

• –320

• –352

• –400

Answer 1

The sum of first 16 terms of the AP: 10, 6, 2, ... is –320.

Explanation:

Given, AP is 10, 6, 2,...

Here,

First term a = 10,

Common difference,

d = – 4

∴ S₁₆ = `16/2[2a + (16 - 1)d]`   ...`[∵ S_n = n/2[2a + (n - 1)d]]`

= 8[2 × 10 + 15(– 4)]

= 8(20 – 60)

= 8(– 40)

= – 320