From the sequence given:
-57,-49,-41,-33...
the common difference, d will be:
-49-(-57)
=8
This implies that the sequence is an arithmetic sequence. The explicit formula is given by:
an=a+d(n-1)
where:
a=first term
d=common difference
n=nth term
from the sequence:
a=-57, d=8
thus the explicit formula for the sequence will be:
an=-57+8(n-1)
simplifying the above we get:
an=-57+8n-8
an=-65+8n
The answer:
An=8n-65