The seventh term of an arithmetic sequence is 10.2 and the twelfth term is 17.7. What is the common difference of the arithmetic sequence?
The common difference is

Use the explicit formula to find a1.
a1 =

What is the explicit formula for the arithmetic sequence?
A: an = 1.2 + (n - 1)1.5
B: an = 1.5 + (n – 1)1.2
C: an = 1.5 + (n – 1)3.9
D: an = 3.9 + (n – 1)1.5

ANSWERS: 1.5, 1.2, A: an = 1.2 + (n – 1)1.5