Page 7 - Number sequence

Question

Consider the following sequence:

13; 28; 43; 58; ….

th
a. Determine the 100 term

b. Evaluate 25 correct to 2 significant figures
5

Solution

a. = + ( − 1)

13; 28; 43; 58; ….
= 13 = 100 = − = − = 28 − 13 = 43 − 28 = 15
3
2
1
2
100 = 13 + (100 − 1)15 = 1498

b. = + ( − 1)

13; 28; 43; 58; ….
We need the value of 25
5
= 13 = − = − = 28 − 13 = 43 − 28 = 15
2
2
3
1
25 = 13 + (25 − 1)15 = 373
25 = 13 + (5 − 1)15 = 73
25 373
= = 5,1 (Correct to 2 significant figures)
5 73