Question

If the first term of an AP is –5 and the common difference is 2, then the sum of the first 6 terms is ______.

Options

• 0

• 5

• 6

• 15

Answer 1

If the first term of an AP is –5 and the common difference is 2, then the sum of the first 6 terms is 0.

Explanation:

Given, `a = -5` and `d = -2`

∴ `S_6 = 6/2 [2a + (6 - 1)d]`  .......`[because  S_n = n/2 (2a + (n - 1)d)]`

= `3[2(-5) + 5(2)]`

= `3(-10 + 10)`

= 0