Question 97661
nth term of an arithmetic sequence is give by
 t(n) = a + (n-1)d where a is the first team of the sequence and d the common difference

for the first series 
a=-4 
d= -2 - (-4)  difference between any 2 successive terms
 = 2

t(n) = -4 + (n-1)2
     = -4 + 2n -2
     = 2n - 6

for the second series 
a=5
and d = 1-5 = -4

the nth term
t(n) = 5 + (n-1)* -4
     = -4n +9