Question

What is the 23th term of the sequence
{20, 16, 12.8, ... }

Answer 1

Explanation:

`an = a1 + (n - 1)d \\ d = a2 - a1 \\ a1 = 20 \\ a2 = 16 \\ d = - 4 \\ an = 20 + (n - 1) * - 4 \\ an = 20 - 4n + 4 \\ an = 24 - 4n \\ a23 = 24 - 4 * 23 \\ a23 = - 68`