Page 6 - Number sequence

Arithmetic Sequences have common difference given by

= −

or

= −

or

= − −

Question

Consider the following sequence:

14; −8; −30; −52; ….
a. Determine the 26 term
th
th
th
b. Determine the sum of the 10 term and 18 term

Solution

a. = + ( − 1)

14; −8; −30; −52; ….

= 14 = 26 = − = −8 − 14 = −22
2
1
26 = 14 + (26 − 1)(−22) = −536

b. = + ( − 1)

14; −8; −30; −52; ….
= 14 = − = −8 − 14 = −22
2
1
= 10 ℎ = 14 + (10 − 1)(−22) = −184
10
= 18 ℎ 14 = 14 + (18 − 1)(−22) = −360
Sum = −184 + (−360) = −544