3.3 CHAPTER 3. SEQUENCES AND SERIES
Or, after how many days would 16 384 people be newly-infected with the flu virus?
an = a 1 .rn−^1
16 384 = 2× 2 n−^1
16 384÷ 2 = 2n−^1
8 192 = 2n−^1
213 = 2n−^1
13 = n− 1
n = 14That is, after 14 days 16 384 people are newly-infected.
Activity: General Equation of Geometric Sequence
Determine the formula for the nth-term of the following geometric sequences:- 5; 10; 20; 40; 80;...
2.^12 ;^14 ;^18 ;... - 7; 28; 112; 448;...
- 2 , 6 , 18 , 54 ,...
5.−3; 30;− 300; 3000;...
Exercise 3 - 1
- What is the important characteristic of an arithmetic sequence?
- Write down how you would go about finding the formula for the nthterm of an arithmetic
sequence? - A single square is made from 4 matchsticks. To make two squares in a row takes 7 matchsticks,
while three squares in arow takes 10 matchsticks. Determine:
(a) the first term
(b) the common difference
(c) the formula for the general term
(d) how many matchsticks are in a row of 25 squares- 5; x; y is an arithmetic sequence and x; y; 81 is a geometric sequence. All terms in the
sequences are integers.Calculate the values of x and y.
More practice video solutions or help at http://www.everythingmaths.co.za(1.) 01cb (2.) 01cc (3.) 01cd (4.) 01ce