Question

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

Answer 1

Answer:

              - 320

Step-by-step explanation:

a₁ = 10

a₂ = 6

d = a₂  - a₁ = 6 - 10 = -4

n = 16

a₁₆ = a₁ + (n-1)•d = 10 + (16-1)•(-4) = 10 - 60 = -50

$S_{n}=\dfrac{a_1+a_n}{2}\cdot n\\\\\\S_{16}=\dfrac{10-50}{2}\cdot 16=-40\cdot8=-320$