Math Problem Statement

lim(x -> (π/2)+) (1/x) sec(x)

Solution

The limit problem you're asking to solve is:

limx(π2)+(1xsecx)\lim_{x \to \left(\frac{\pi}{2}\right)^+} \left( \frac{1}{x} \sec x \right)

Step-by-Step Solution:

  1. Examine the behavior as xπ2+x \to \frac{\pi}{2}^+:

    • The secant function, secx=1cosx\sec x = \frac{1}{\cos x}, becomes undefined at x=π2x = \frac{\pi}{2}, because cos(π2)=0\cos \left( \frac{\pi}{2} \right) = 0.
    • As xπ2+x \to \frac{\pi}{2}^+ (from the right-hand side), cosx\cos x approaches 0 from the negative side (since cosine is negative in the second quadrant). Therefore, secx\sec x tends to -\infty.
  2. Analyze 1x\frac{1}{x} as xπ2+x \to \frac{\pi}{2}^+:

    • As xx approaches π2\frac{\pi}{2} from the right, 1x\frac{1}{x} approaches some finite positive number (because xx is still positive).
  3. Combine the behavior:

    • As xπ2+x \to \frac{\pi}{2}^+, 1x\frac{1}{x} stays finite and positive, but secx\sec x tends to -\infty.
    • Multiplying a positive number by -\infty gives -\infty.

Final Result:

limx(π2)+(1xsecx)=\lim_{x \to \left( \frac{\pi}{2} \right)^+} \left( \frac{1}{x} \sec x \right) = -\infty

Would you like more details or explanations on any step?

Related Questions:

  1. What happens to 1xsecx\frac{1}{x} \sec x if xπ2x \to \frac{\pi}{2}^- (from the left)?
  2. How does the behavior of secant change in different quadrants of the unit circle?
  3. Can you use L'Hopital's Rule for this type of limit?
  4. What are the typical discontinuities of the secant function?
  5. What is the behavior of secx\sec x for values of xx near 00?

Tip: Always check if the function inside a limit has discontinuities or singularities at the point you're evaluating the limit for accurate results.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometric Functions

Formulas

sec(x) = 1/cos(x)

Theorems

Limit Theorem for Trigonometric Functions

Suitable Grade Level

Grades 11-12 or introductory college level