Math Problem Statement

Calculate the limit: lim (12x - 2π) / (5 sin 2x) as x approaches π.

Solution

The expression you provided is:

limxπ12x2π5sin2x\lim_{{x \to \pi}} \frac{{12x - 2\pi}}{{5 \sin 2x}}

Step-by-step solution:

  1. Substitute x=πx = \pi directly:

    • Numerator: 12π2π=10π12\pi - 2\pi = 10\pi
    • Denominator: 5sin(2π)5 \sin(2\pi)

    Since sin(2π)=0\sin(2\pi) = 0, the denominator becomes 0, leading to an undefined form (infinity or a division by zero).

  2. Analyze the limit: Since direct substitution leads to division by zero, this suggests we may have to apply L'Hopital's Rule because the limit is of the indeterminate form 00\frac{0}{0}.

  3. Differentiate numerator and denominator:

    • The derivative of the numerator 12x2π12x - 2\pi is 1212.
    • The derivative of the denominator 5sin(2x)5 \sin(2x) is 10cos(2x)10 \cos(2x) (using the chain rule).
  4. Recompute the limit: limxπ1210cos(2x)\lim_{{x \to \pi}} \frac{{12}}{{10 \cos(2x)}}

    • At x=πx = \pi, cos(2π)=1\cos(2\pi) = 1.

    Therefore, the limit becomes: 1210=1.2\frac{{12}}{{10}} = 1.2

Final Answer:

limxπ12x2π5sin2x=1.2\lim_{{x \to \pi}} \frac{{12x - 2\pi}}{{5 \sin 2x}} = 1.2

Would you like further details on this solution or have any specific questions?

Here are five related questions to deepen your understanding:

  1. What is L'Hopital's Rule, and when can it be applied?
  2. How do you differentiate trigonometric functions like sin(2x)\sin(2x)?
  3. What are common indeterminate forms in limits, and how do we resolve them?
  4. Why does sin(2π)=0\sin(2\pi) = 0 and cos(2π)=1\cos(2\pi) = 1?
  5. Can L'Hopital's Rule always be used, or are there exceptions?

Tip: When you encounter an indeterminate form like 00\frac{0}{0}, consider using L'Hopital's Rule, but ensure both the numerator and denominator approach zero or infinity.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometry
Differentiation

Formulas

L'Hopital's Rule: lim (f(x)/g(x)) = lim (f'(x)/g'(x)) if lim f(x)/g(x) is 0/0 or ∞/∞
Trigonometric functions: sin(2x), cos(2x)

Theorems

L'Hopital's Rule

Suitable Grade Level

Grade 11-12 (High School Calculus)