Question

Write down in terms of n, an expression for the nth term

of the following sequences:
a) 4 1 -2 -5 -8
b) -7 -12 -17 -22 -27

Answer 1

a) -3n + 7

b) -5n -2

Explanation:

a) 4 1 -2 -5 -8

the difference = -3

the -3 times table = -3, -6, -9, -12 etc

from -3 to 4 we add 7

answer = -3n + 7

check = -3(4) + 7 should give -5 (because -5 is the 4th term in the sequence)

b) -7 -12 -17 -22 -27

the difference = -5

-5 times table = -5, -10, -15, -20

from -5 to -7 we subtract 2

answer = -5n -2

check = -5(5)-2 should give -27 (because -27 is the 5th term in the sequence)