(1+x)(1+x^2)(1+x^3)(1+x^4)

3 min read Jun 16, 2024
(1+x)(1+x^2)(1+x^3)(1+x^4)

Expanding the Product (1+x)(1+x^2)(1+x^3)(1+x^4)

This article will explore the expansion of the product (1+x)(1+x^2)(1+x^3)(1+x^4). We will use the distributive property and discuss patterns that emerge in the expansion.

Expanding the Product Step-by-Step

  1. Start with the first two factors: (1+x)(1+x^2) = 1 + x^2 + x + x^3 = 1 + x + x^2 + x^3

  2. Multiply the result by the third factor: (1 + x + x^2 + x^3)(1+x^3) = 1 + x^3 + x + x^4 + x^2 + x^5 + x^3 + x^6 = 1 + x + x^2 + 2x^3 + x^4 + x^5 + x^6

  3. Finally, multiply the result by the fourth factor: (1 + x + x^2 + 2x^3 + x^4 + x^5 + x^6)(1+x^4) = 1 + x^4 + x + x^5 + x^2 + x^6 + 2x^3 + 2x^7 + x^4 + x^8 + x^5 + x^9 + x^6 + x^10 = 1 + x + x^2 + 2x^3 + 2x^4 + 2x^5 + 2x^6 + 2x^7 + x^8 + x^9 + x^10

Observations and Patterns

  • Coefficients: Notice that most of the coefficients are 1 or 2. This is because each term is generated by multiplying a combination of 'x' terms from the original factors.
  • Exponents: The exponents in the final expansion range from 0 to 10. This makes sense as the highest power of x in the original product is x^4 * x^3 * x^2 * x = x^10.

Generalization

The expansion of the product (1+x)(1+x^2)(1+x^3)...(1+x^n) will have the following characteristics:

  • Exponents: The exponents will range from 0 to the sum of the exponents in the original factors.
  • Coefficients: The coefficients will be determined by the number of ways to combine 'x' terms from the original factors to get the desired exponent.

While calculating the exact coefficients for a large 'n' can be complex, understanding these patterns can help simplify the process.

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