2054 /www/nrich/html/content/04/weekly/prob5/ 1 2012-09-17T12:33:24 <?xml version="1.0" encoding="UTF-8"?> <mdoxml version="1.0"><br></br> <p>The standard Fibonacci sequence 1, 1, 2, 3, 5, 8, 13, ? begins with two 1s and each later number in the sequence is the sum of the previous two numbers. Other Fibonacci-like sequences can be constructed by starting with any two numbers a and b (not necessarily 1 and 1) and using the same rule for creating the other numbers in the sequence. What is the first term of the Fibonacci-like sequence whose second term is 4 and whose fifth term is 22?</p> If you liked this problem, <a href="http://nrich.maths.org/7024">here is an NRICH task</a> which challenges you to use similar mathematical ideas.<br></br></mdoxml> <?xml version="1.0" encoding="UTF-8"?> <mdoxml version="1.0"><p>Let the first term be x, then the sequence is x, x+4, x+8, 2x+12. So 2x+12=22 and hence x=5.</p> </mdoxml> 2 3 0 0 1 0 0 Weekly Problem 40 - 2012