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Ch. 5 - Complex Numbers, Polar Coordinates and Parametric Equations
Blitzer - Trigonometry 3rd Edition
Blitzer3rd EditionTrigonometryISBN: 9780137316601Not the one you use?Change textbook
Chapter 5, Problem 5.1.49

In Exercises 37–52, perform the indicated operations and write the result in standard form.
√(−8) (√(−3) − √5 )

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1
Recognize that the expression involves square roots of negative numbers, which means we are working with imaginary numbers. Recall that \(\sqrt{-a} = \sqrt{a} \cdot i\), where \(i\) is the imaginary unit with the property \(i^2 = -1\).
Rewrite each square root of a negative number in terms of \(i\): \(\sqrt{-8} = \sqrt{8} \cdot i\) and \(\sqrt{-3} = \sqrt{3} \cdot i\).
Substitute these into the expression: \(\sqrt{-8} (\sqrt{-3} - \sqrt{5}) = (\sqrt{8} \cdot i) \times (\sqrt{3} \cdot i - \sqrt{5})\).
Distribute \(\sqrt{8} \cdot i\) across the terms inside the parentheses: \(\sqrt{8} \cdot i \times \sqrt{3} \cdot i - \sqrt{8} \cdot i \times \sqrt{5}\).
Simplify each term: For the first term, multiply the square roots and \(i \times i = i^2 = -1\). For the second term, multiply the square roots and keep the \(i\). Then combine like terms to write the result in standard form \(a + bi\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Complex Numbers and Imaginary Unit

Complex numbers include a real part and an imaginary part, where the imaginary unit i is defined as √−1. Expressions involving square roots of negative numbers can be rewritten using i, for example, √−8 = √8 × i = 2√2 i. Understanding this allows simplification of roots of negative numbers into complex form.
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Operations with Complex Numbers

Performing operations like multiplication and addition with complex numbers requires applying distributive property and combining like terms. When multiplying expressions involving i, remember that i² = −1, which helps convert powers of i into real numbers or simpler imaginary terms.
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Standard Form of Complex Numbers

The standard form of a complex number is a + bi, where a and b are real numbers. After performing operations, the result should be expressed in this form by separating the real and imaginary parts clearly, facilitating easier interpretation and further calculations.
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