Question

Find the sum of the AP 9, 7, 5, 3,…..to 14 terms.

Answer 1

Sum of n terms of AP formula:

Where

First term = a

Common difference = d

Number of terms = n

9, 7, 5, 3,…..to 14 terms.

a = 9

d = 7 – 9 – -2

Using (1)

S₁₄ = 14/2 [2(9) + (14 – 1)(-2)]

= (7)(18 – 26)

= – 56

Sum of 14 terms of this AP is – 56.