2 Express ( √5 - √5₂) in 2 simplest a + bi form.

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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The problem presented is:

Express \(\left( \frac{\sqrt{5}}{5} - \frac{\sqrt{5}}{2}i \right)^2\) in simplest \(a + bi\) form.

To solve this, expand the expression using the formula for the square of a binomial:

\[
(a - bi)^2 = a^2 - 2abi + (bi)^2
\]

Substitute \(a = \frac{\sqrt{5}}{5}\) and \(b = \frac{\sqrt{5}}{2}\):

1. Calculate \(a^2\):
   \[
   a^2 = \left(\frac{\sqrt{5}}{5}\right)^2 = \frac{5}{25} = \frac{1}{5}
   \]

2. Calculate \((bi)^2\):
   \[
   (bi)^2 = \left(\frac{\sqrt{5}}{2}i\right)^2 = -\left(\frac{5}{4}\right) = -\frac{5}{4}
   \]

3. Calculate \(-2abi\):
   \[
   -2abi = -2 \times \frac{\sqrt{5}}{5} \times \frac{\sqrt{5}}{2}i = -\frac{2 \times 5}{10}i = -i
   \]

Combine these results:

\[
\left(\frac{\sqrt{5}}{5} - \frac{\sqrt{5}}{2}i\right)^2 = \frac{1}{5} - i - \frac{5}{4}
\]

Simplify the real and imaginary parts:

- Real part: \(\frac{1}{5} - \frac{5}{4} = \frac{4}{20} - \frac{25}{20} = -\frac{21}{20}\)
- Imaginary part: \(-i\)

Thus, the expression in the simplest \(a + bi\) form is:

\[
-\frac{21}{20} - i
\]
Transcribed Image Text:The problem presented is: Express \(\left( \frac{\sqrt{5}}{5} - \frac{\sqrt{5}}{2}i \right)^2\) in simplest \(a + bi\) form. To solve this, expand the expression using the formula for the square of a binomial: \[ (a - bi)^2 = a^2 - 2abi + (bi)^2 \] Substitute \(a = \frac{\sqrt{5}}{5}\) and \(b = \frac{\sqrt{5}}{2}\): 1. Calculate \(a^2\): \[ a^2 = \left(\frac{\sqrt{5}}{5}\right)^2 = \frac{5}{25} = \frac{1}{5} \] 2. Calculate \((bi)^2\): \[ (bi)^2 = \left(\frac{\sqrt{5}}{2}i\right)^2 = -\left(\frac{5}{4}\right) = -\frac{5}{4} \] 3. Calculate \(-2abi\): \[ -2abi = -2 \times \frac{\sqrt{5}}{5} \times \frac{\sqrt{5}}{2}i = -\frac{2 \times 5}{10}i = -i \] Combine these results: \[ \left(\frac{\sqrt{5}}{5} - \frac{\sqrt{5}}{2}i\right)^2 = \frac{1}{5} - i - \frac{5}{4} \] Simplify the real and imaginary parts: - Real part: \(\frac{1}{5} - \frac{5}{4} = \frac{4}{20} - \frac{25}{20} = -\frac{21}{20}\) - Imaginary part: \(-i\) Thus, the expression in the simplest \(a + bi\) form is: \[ -\frac{21}{20} - i \]
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