Continued fractions—stacks of fractions that never end—have been studied by some of the greatest mathematicians, including Euler and Lagrange, as well as Galois. Let's take a closer look at these fractions and their strange denominators.
Consider the equation *x 2 + x – 1 = 0. A calculation shows that its unique positive solution is (5−1)/2.
This equation is equivalent to x (x* + 1) = 1, and hence to x=1+x1.
Now replace the x in the denominator with 1+x1, giving x=1+1+x11.
There is nothing to stop us repeating the process again and again, suggesting that x can be written as a fraction that "never ends"—what is known as a continued fraction: