Exploring And Explaining Infinite Roots

Lucas Potrykus
ILLUMINATION
Published in
3 min readJul 31, 2023
Photo by Steve Johnson on Unsplash

In mathematics, the concept of infinite roots lies at the heart of understanding sequences and their convergence properties (and everyone is interested by the concept of infinity). The idea of taking repeated roots of a number or expression extends our understanding of arithmetic beyond finite processes. So, let’s get into it!

Defining Infinite Roots

Let us begin by understanding what we mean by infinite roots. Given a number a and a positive integer n, the notation a¹/n ​ represents the nth root of a. For instance, a^1/2​ is the square root of a, and a¹/3​ denotes the cube root of a.

Now, what happens when we repeatedly take the root of a number, let’s say, n times? This process leads us to the concept of infinite roots, where we continuously apply the root operation to a number to explore its behavior as n approaches infinity. Ok, still simple right?

Infinite Square Root

To illustrate the concept, let’s consider the infinite square root of a number x:

Screenshot taken by author from online personal notebook

As we take the square root repeatedly, the exponents of the radicals form a geometric sequence with a common ratio of 1/2​:

Screenshot taken by author from online personal notebook

We can represent the general term of this sequence as 1/2^n. As n approaches infinity, the exponent tends to zero, making the infinite square root equivalent to:

Screenshot taken by author from online personal notebook

Infinite Cube Root

Next, let’s explore the infinite cube root of a number y:

Screenshot taken by author from online personal notebook

The exponents of the radicals now form a geometric sequence with a common ratio of 1/3​:

Screenshot taken by author from online personal notebook

In the limit as n approaches infinity, the exponent tends to zero:

Screenshot taken by author from online personal notebook

Infinite Root of a Polynomial

The concept of infinite roots is not limited to numbers alone (surprise, surprise); it also extends to polynomials. Consider the polynomial function f(x)=x^n, where n is a positive integer. As n approaches infinity, the polynomial f(x) exhibits the behavior of an “infinite root” at x=1:

Screenshot taken by author from online personal notebook

This result is particularly fascinating, as the polynomial f(x) approaches a constant value regardless of the value of x. Ok, so it got a little harder but still: very fascinating stuff!

Done!

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