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Question

Which of the following is the correct representation of the given expression?
$$ \frac{(1 + i)^8}{(1 - i)^6} $$

The correct answer is
$2e^{-i\frac{\pi}{2}}$

To solve the expression \( \frac{(1 + i)^8}{(1 - i)^6} \) and determine its correct representation, we will utilize Euler's formula and properties of complex numbers.

  1. Express \( 1 + i \) and \( 1 - i \) in polar form:
    • \(1 + i = \sqrt{2} \, e^{i \frac{\pi}{4}}\)
    • \(1 - i = \sqrt{2} \, e^{-i \frac{\pi}{4}}\)
  2. Substitute these into the expression:

\(\frac{(1 + i)^8}{(1 - i)^6} = \frac{(\sqrt{2} \, e^{i \frac{\pi}{4}})^8}{(\sqrt{2} \, e^{-i \frac{\pi}{4}})^6}\)

  1. Simplify the numerator and the denominator:
    • Numerator: \( (\sqrt{2})^8 \, (e^{i \frac{\pi}{4}})^8 = 16 \, e^{i 2\pi} = 16 \)
    • Denominator: \( (\sqrt{2})^6 \, (e^{-i \frac{\pi}{4}})^6 = 8 \, e^{-i \frac{3\pi}{2}} = 8 \, e^{i \frac{\pi}{2}} \)
  2. Compute the final expression:

\(\frac{16}{8} \cdot \left( \frac{1}{e^{i \frac{\pi}{2}}} \right) = 2 \, e^{-i \frac{\pi}{2}}\)

  1. Thus, the expression simplifies to \(2 \, e^{-i \frac{\pi}{2}}\).

This matches option:

$2e^{-i\frac{\pi}{2}}$

  1. .

 

Therefore, the correct representation of the expression is $2e^{-i\frac{\pi}{2}}$, making it the correct answer.

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Important Questions from Complex Numbers

  1. Consider the following complex numbers
    $$ z_1 = r_1(\cos \theta_1 + i \, \sin \theta_1) $$
    $$ z_2 = r_2(\cos \theta_2 + i \, \sin \theta_2) $$
    where $r_1, r_2$ are real numbers, $0 \leq \theta_1 \leq \frac{\pi}{2}$, $0 \leq \theta_2 \leq \frac{\pi}{2}$, and $i = \sqrt{-1}$
    If $|z_1 + z_2| = |z_1| + |z_2|$, which one of the following conditions is necessarily CORRECT?
  2. What is the value of \((2 - 3i) + (3 + 5i)\)
  3. What is the real part of the number \(15 + 2i\)
  4. What is the real part of the number $5i$?
  5. What is the value of $(6 + 3i) + (2 + 5i)$?
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