Chapter 1: Problem 8
Find the discontinuities, if any. $$f(x)=\sqrt{2+\tan ^{2} x}$$
Short Answer
Expert verified
Discontinuities are at \( x = \frac{\pi}{2} + k\pi \), integer \( k \).
Step by step solution
01
Understand the Function
The function given is \( f(x) = \sqrt{2 + \tan^2 x} \). To identify discontinuities, we need to determine where the square root and tangent functions cause issues, such as undefined values or non-real numbers.
02
Square Root Function Analysis
The expression under the square root, \( 2+\tan^2 x \), must be non-negative for \( f(x) \) to be defined. Since \( \tan^2 x \geq 0 \) for all \( x \), \( 2+\tan^2 x \geq 2 \) is always non-negative. Therefore, the square root itself does not cause any discontinuities.
03
Analyze the Tangent Function
The tangent function, \( \tan x \), is undefined where \( \cos x = 0 \). This occurs at odd multiples of \( \frac{\pi}{2} \) (i.e., \( x = \frac{\pi}{2} + k\pi \), where \( k \) is an integer). At these points, \( \tan x \) is undefined, leading to undefined values for \( f(x) \) as well.
04
Conclusion: Identify Discontinuities
The only discontinuities occur where the tangent function is undefined, due to division by zero in \( \tan x = \frac{\sin x}{\cos x} \). Thus, \( f(x) \) is discontinuous at odd multiples of \( \frac{\pi}{2} \): \( x = \frac{\pi}{2} + k\pi \) for integer \( k \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Tangent Function
The tangent function, denoted as \( \tan x \), is a fundamental trigonometric function. It is mathematically represented as the ratio of the sine function \( \sin x \) to the cosine function \( \cos x \). Due to this ratio form, \( \tan x \) becomes undefined whenever \( \cos x \) equals zero. This situation occurs at specific values of \( x \), namely when \( x = \frac{\pi}{2} + k\pi \), where \( k \) is any integer. At these points, the cosine function is zero, leading to division by zero, which results in the tangent becoming undefined.
- The periodicity of the tangent function is \( \pi \), meaning its pattern repeats every \( \pi \) units.
- It exhibits vertical asymptotes at each undefined point.
Square Root Function
The square root function is symbolized by \( \sqrt{} \), which operates by extracting the non-negative root of a given expression. When dealing with square roots, it is crucial for the expression inside, called the radicand, to be non-negative. This means any negative values under a square root would result in non-real numbers. For the function \( f(x) = \sqrt{2 + \tan^2 x} \), the radicand is \( 2 + \tan^2 x \).
- Because \( \tan^2 x \) is always non-negative, \( 2 + \tan^2 x \) is always greater than or equal to 2. Therefore, it does not cause any discontinuities.
- The domain of the square root function here is all real numbers where the radicand remains non-negative.
Undefined Values
Undefined values in a function typically arise from division by zero or taking the square root of negative numbers. For the function \( f(x) = \sqrt{2 + \tan^2 x} \), undefined values originate due to the behavior of the tangent function. As previously mentioned, \( \tan x \) is undefined wherever its denominator, \( \cos x \), hits zero, which are the points \( x = \frac{\pi}{2} + k\pi \).
- At these points, \( \tan x \) would lead to an undefined situation, thereby affecting \( f(x) \).
- These critical points are also where the square root function encounters discontinuities in this context.
- Discontinuities often imply gaps or breaks in the function's graph, precisely where these undefined values occur.