Determine the common difference and zero term

Question

For the arithmetic sequence below determine the common difference and write the explicit rule.

1. -5,-2.5,0,2.5,5
2. what is the zero term of this sequence?
3. what is the explicit rule of this sequence?

Answer 1

Each number is 2.5 more than the previous difference, so the common difference (d) is 2.5.

The zero term of this sequence (a1) is the first term, -5

The explicit rule for an arithmetic sequence: an = a1 + (n-1)d

an = -5 + (n-1)2.5

an = -5 + 2.5n - 2.5

an = -7.5 + 2.5n