Question

given the following sequences : -17 -25 -33 -41... write an explicit formula and find the 28th term in this sequence

Answer 1

a(n) = -8n -9

a(28) = -233

Explanation:

a(n) = a(1) + (n - 1)d

n is the nth term, a(1) is the first term, d is the common difference.

*d = -25 - (-17) = -8

a(n) = -17 + (n - 1)(-8)

= -17 + (-8n + 8)

= -17 - 8n + 8

= -8n - 9

For the 28th term

a(28) = -8(28) - 9

= -224 - 9

= -233