Answer:
In bold below.
Step-by-step explanation:
a) 12 10 8 6 4
This is an arithmetic sequence with common difference -2.
nth term = a1 + (n - 1)d
= 12 + (n - 1)-2
= 12 -2n + 2
= -2n + 14.
b) 25 20 15 10 5
This is an arithmetic sequence with common difference -5.
nth term = a1 + (n - 1)d
= 25 + (n - 1)-5
= 25 - 5n + 5
= -5n + 30.
