(1+x)(1+x^2)(1+x^4)(1+x^8)

4 min read Jun 16, 2024
(1+x)(1+x^2)(1+x^4)(1+x^8)

Exploring the Pattern: (1+x)(1+x^2)(1+x^4)(1+x^8)

This expression, (1+x)(1+x^2)(1+x^4)(1+x^8), presents a fascinating pattern. Let's delve into its properties and explore how it can be simplified.

The Power of Observation

Notice the increasing powers of x in each factor. We have x, x^2, x^4, and x^8 - each term is the square of the previous one. This suggests a connection to the concept of geometric series.

Expanding the Expression

Let's expand the expression step by step:

  1. First two factors: (1+x)(1+x^2) = 1 + x + x^2 + x^3
  2. Multiply by the third factor: (1 + x + x^2 + x^3)(1+x^4) = 1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7
  3. Multiply by the final factor: (1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7)(1+x^8) = 1 + x + x^2 + x^3 + x^4 + x^5 + x^6 + x^7 + x^8 + x^9 + x^10 + x^11 + x^12 + x^13 + x^14 + x^15

A Clear Pattern Emerges

The result is a polynomial with terms ranging from x^0 (which is 1) to x^15. Observe that all the odd powers of x are present, and the even powers are absent. This is a direct consequence of the pattern in the original factors.

The Generalization

We can generalize this for any number of factors following the same pattern. For example:

(1+x)(1+x^2)(1+x^4)(1+x^8)...(1+x^(2^n))

This expression will result in a polynomial with terms from x^0 to x^(2^(n+1) - 1), where all the odd powers of x are present, and all the even powers are absent.

Significance and Applications

This expression demonstrates a neat application of the principles of geometric series and polynomial expansion. It helps visualize how multiplying factors with increasing powers can lead to predictable patterns in the resulting polynomial. Such patterns are often utilized in mathematical proofs and derivations, as well as in various areas like signal processing and computer science.

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