Math 115

Quiz 9 Name: key

Note: you may find it helpful to make a list of the first several Fibonacci numbers in the margin


1.       Compute the following (


This is: the 6th Fibonacci number + 2 = 8+2=10




This is: The (6+2)nd = 8th Fibonacci number, or 21



2.       Let denote the golden ratio, , as usual. Calculate (on your calculator, please!) and give your answer to 5 decimal places:



3.       For the sequence that begins {10, 20, 30, 40, }

a.       Give a recursive formula for an:

along with the initial condition: a1=10



b.      Given an explicit formula for an:




4.       Find the dimensions of the shaded rectangle to make it a gnomon for the white rectangle:



6 inches (Note: figure not

drawn to scale)


2 inches

The larger rectangle (white and shaded combined) must be 3 times as long as it is tall, so it is 18 inches long

This makes the shaded part 6 inches tall and 16 inches long.