Skip to main content
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 31

In Exercises 29–36, simplify and write the result in standard form. ____ √−108

Verified step by step guidance
1
Recognize that the expression involves the square root of a negative number, which means the result will be a complex number. Recall that \(\sqrt{-a} = \sqrt{a} \times i\), where \(i\) is the imaginary unit with the property \(i^2 = -1\).
Rewrite the expression \(\sqrt{-108}\) as \(\sqrt{108} \times i\) to separate the imaginary unit from the real number under the root.
Simplify \(\sqrt{108}\) by factoring 108 into its prime factors or perfect squares. For example, \(108 = 36 \times 3\), and since \(\sqrt{36} = 6\), you can write \(\sqrt{108} = \sqrt{36 \times 3} = 6\sqrt{3}\).
Substitute back to get the expression in terms of \(i\): \(\sqrt{-108} = 6\sqrt{3} \times i\).
Write the final answer in standard form for complex numbers, which is \(a + bi\). Since there is no real part here, the expression is \(0 + 6\sqrt{3}i\).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

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

Simplifying Square Roots of Negative Numbers

When simplifying the square root of a negative number, recognize that it involves imaginary numbers. The square root of a negative number can be expressed as the product of the imaginary unit 'i' (where i² = -1) and the square root of the corresponding positive number.
Recommended video:
2:20
Imaginary Roots with the Square Root Property

Prime Factorization for Simplifying Radicals

To simplify a square root, break down the number inside the root into its prime factors. Pair factors to extract them from under the root, simplifying the expression. For example, √108 can be factored into √(36 × 3) = 6√3.
Recommended video:
6:08
Factoring

Standard Form of Complex Numbers

The standard form of a complex number is a + bi, where 'a' is the real part and 'b' is the imaginary coefficient. After simplifying the radical, express the result in this form to clearly separate real and imaginary components.
Recommended video:
04:47
Complex Numbers In Polar Form