(1+i)^2n+(1-i)^2n

4 min read Jun 16, 2024
(1+i)^2n+(1-i)^2n

Exploring the Properties of (1+i)^2n + (1-i)^2n

This article delves into the fascinating properties of the expression (1+i)^2n + (1-i)^2n, where 'i' represents the imaginary unit (√-1) and 'n' is any integer. We will uncover a surprising pattern and explore the significance of this expression.

Expanding the Expression

To begin, let's expand the expression using the binomial theorem:

(1+i)^2n = (1 + 2ni + (2n)(2n-1)/2! * i^2 + ... + i^2n)

(1-i)^2n = (1 - 2ni + (2n)(2n-1)/2! * i^2 + ... + i^2n)

Notice that the terms involving odd powers of 'i' cancel out when we add these two expansions. This is because the coefficients of the odd terms are the same but with opposite signs.

Simplifying with i^2

Recall that i^2 = -1. Therefore, even powers of 'i' can be simplified as follows:

  • i^2 = -1
  • i^4 = (i^2)^2 = (-1)^2 = 1
  • i^6 = (i^2)^3 = (-1)^3 = -1
  • i^8 = (i^2)^4 = (-1)^4 = 1

...and so on. We can see that even powers of 'i' cycle through the values -1 and 1.

Finding the Pattern

Using these simplifications, we can rewrite the expression as:

(1+i)^2n + (1-i)^2n = (1 + 2n(-1) + (2n)(2n-1)/2! * (-1)^2 + ... + (-1)^n) + (1 - 2n(-1) + (2n)(2n-1)/2! * (-1)^2 + ... + (-1)^n)

Now, notice that all the terms with odd powers of 'n' cancel out, leaving only the terms with even powers of 'n'. We are left with:

(1+i)^2n + (1-i)^2n = 2 * [1 + (2n)(2n-1)/2! * 1 + (2n)(2n-1)(2n-2)(2n-3)/4! * 1 + ... + (-1)^n]

A Surprising Result

The expression within the square brackets is simply the expansion of (1 + 1)^2n, which is 2^2n. Therefore, we have:

(1+i)^2n + (1-i)^2n = 2 * 2^2n = 2^(2n+1)

Conclusion

This elegant result reveals a powerful connection between complex numbers and simple arithmetic. The expression (1+i)^2n + (1-i)^2n simplifies to 2^(2n+1), demonstrating a surprising pattern and showcasing the intricate beauty of mathematical relationships. This knowledge can be valuable for solving various problems involving complex numbers and exploring further mathematical concepts.

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