Question

Here is the rule for a sequence.

21
After the first two terms, each term is the sum of the previous two terms
The 1st term is 33
The 2nd term is x
The 4th term is 73
Work out the value of x.
[3 marks]

Answer 1

20

Explanation:

Because of the rule the sum of x and term 3 must be 73. The sum of term 3 must be x and 33. Term 3 will be y.

x + 33 = y

x + y = 73

Now set the terms to equal each other

x + 33 = y

x + y = 73 --> y = 73 - x

x + 33 = 73 - x

2x + 33 = 73

2x = 40

x = 20

x + y = 73

20 + y = 73

y = 53