Math Problem Statement

Find the value of lim(x→0) 5x / sin(x/5).

Solution

The given mathematical expression is:

limx05xsinx5\lim_{x \to 0} \frac{5x}{\sin{\frac{x}{5}}}

Solution:

We use the standard limit property:

limu0sinuu=1\lim_{u \to 0} \frac{\sin u}{u} = 1

Let u=x5u = \frac{x}{5}, so as x0x \to 0, we also have u0u \to 0. Rewriting the given limit:

limx05xsinx5=limx05xsinu\lim_{x \to 0} \frac{5x}{\sin{\frac{x}{5}}} = \lim_{x \to 0} \frac{5x}{\sin u}

Since u=x5u = \frac{x}{5}, we can substitute:

limx05xsinu=limu05(5u)sinu\lim_{x \to 0} \frac{5x}{\sin u} = \lim_{u \to 0} \frac{5(5u)}{\sin u}

=limu055usinu= \lim_{u \to 0} 5 \cdot \frac{5u}{\sin u}

Using the limit property sinuu1\frac{\sin u}{u} \approx 1 as u0u \to 0, we get:

=5×5=25= 5 \times 5 = 25

Final Answer:

limx05xsinx5=25\lim_{x \to 0} \frac{5x}{\sin{\frac{x}{5}}} = 25

Would you like further clarifications or step-by-step breakdowns?

Related Questions:

  1. What is the general limit property of sinxx\frac{\sin x}{x} as x0x \to 0?
  2. How does the substitution method work for limits?
  3. What are the conditions for using L'Hôpital’s Rule in limits?
  4. Can we use Taylor series to evaluate this limit?
  5. What are some common trigonometric limits used in calculus?

Tip:

When dealing with limits involving trigonometric functions, always check if standard limit properties like limx0sinxx=1\lim_{x \to 0} \frac{\sin x}{x} = 1 can simplify the expression before applying more advanced techniques.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometry
Substitution

Formulas

lim(u→0) sin(u)/u = 1

Theorems

Limit properties of trigonometric functions

Suitable Grade Level

Grades 11-12