Question

What is the 20th term of the arithmetic sequence?

Answer 1

You just need to substitute 20 for x and then solve.

a(20) = -5 +(20-1)3

Simplify: a(20) = -5 + (60-3)

Simplify: a(20) = -5 + 57

Result: a(20) = 52

So, 52 is the 20th term of the arithmetic sequence.

Answer 2

In the equation
$a(n) = - 5 + (n - 1)3$
Let n=20 and evaluate it as:

$a(20) = - 5 + (20 - 1)3 \\ \\ a(20) = - 5 + (19)3 \\ \\ a(20) = - 5 + 57 \\ \\ a(20) = 52$