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Question

Find the value of $(1+i)^4$.

The correct answer is

$-4$

Finding the Value of $(1+i)^4$

This section provides a detailed step-by-step explanation to find the value of the complex number expression $(1+i)^4$. We will simplify the expression using basic algebraic rules and the properties of the imaginary unit, $i$.

Understanding Powers of Complex Numbers

A complex number is typically written in the form $a + bi$, where '$a$' is the real part, '$b$' is the imaginary part, and '$i$' is the imaginary unit. The imaginary unit $i$ is defined such that $i^2 = -1$. To find the value of $(1+i)^4$, we need to multiply $(1+i)$ by itself four times.

Method: Step-by-Step Simplification

A common strategy for calculating higher powers of complex numbers is to first compute the square of the base number and then square the result. This simplifies the process.

Step 1: Calculate the square, $(1+i)^2$

We can expand $(1+i)^2$ using the binomial expansion formula $(a+b)^2 = a^2 + 2ab + b^2$.

Here, $a = 1$ and $b = i$. Applying the formula:

$ (1+i)^2 = 1^2 + 2(1)(i) + i^2 $

Recall that $i^2 = -1$. Substitute this value into the equation:

$ (1+i)^2 = 1 + 2i + (-1) $

Now, simplify the expression by combining the real terms:

$ (1+i)^2 = 1 + 2i - 1 $ $ (1+i)^2 = 2i $

So, we found that $(1+i)^2$ simplifies to $2i$.

Step 2: Calculate $(1+i)^4$ using the result from Step 1

We can rewrite $(1+i)^4$ as $((1+i)^2)^2$. This allows us to use the result we just calculated.

$ (1+i)^4 = \left( (1+i)^2 \right)^2 $

Substitute the value $(1+i)^2 = 2i$ into the equation:

$ (1+i)^4 = (2i)^2 $

Now, we need to square the complex number $2i$. This means squaring both the coefficient (2) and the imaginary unit ($i$):

$ (2i)^2 = 2^2 \times i^2 $

Calculate the squares:

$ (2i)^2 = 4 \times i^2 $

Again, substitute $i^2 = -1$:

$ (2i)^2 = 4 \times (-1) $

Performing the final multiplication:

$ (2i)^2 = -4 $

Therefore, the value of $(1+i)^4$ is $-4$.

Summary of the Calculation

The process to find the value of $(1+i)^4$ involved two main steps:

  • First, we computed $(1+i)^2$, which resulted in $2i$.
  • Second, we squared this result $(2i)^2$, which yielded $-4$.

This step-by-step approach simplifies the calculation of powers for complex numbers.

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Important Questions from Imaginary Number i and its properties

  1. Find the value of (1 - i/1 + i), where 'i' is an imaginary number:

  2. If i = √-1, then how many values does i -2n have for different n ∈ ℤ?

  3. What is \(\rm \sum\limits_{n=1}^{8n+7} i^n\)  equal to, where i = √-1?

  4. What is \(i \times i^4 \times i^9 \times i^{16} \times \ldots \times i^{576}\), where \(i=\sqrt{-1}\), equal to?

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