Math Problem Statement

\lim _{x\to 0}\frac{sin\left(2x\right)}{x}

Solution

To solve the limit limx0sin(2x)x\lim_{x \to 0} \frac{\sin(2x)}{x}, let's proceed step-by-step using limit properties and trigonometric identities.

Step-by-Step Solution

  1. Use Substitution: Let's make a substitution to help simplify the limit. Set u=2xu = 2x. As x0x \to 0, u0u \to 0 as well.

    Rewrite the expression in terms of uu: limx0sin(2x)x=limu0sin(u)u2\lim_{x \to 0} \frac{\sin(2x)}{x} = \lim_{u \to 0} \frac{\sin(u)}{\frac{u}{2}}

  2. Simplify the Expression: The expression sin(u)u2\frac{\sin(u)}{\frac{u}{2}} can be simplified by multiplying the numerator and the denominator by 2: limu0sin(u)u2=limu02sin(u)u\lim_{u \to 0} \frac{\sin(u)}{\frac{u}{2}} = \lim_{u \to 0} \frac{2\sin(u)}{u}

  3. Apply the Sine Limit Identity: We know from the standard limit identity that limu0sin(u)u=1\lim_{u \to 0} \frac{\sin(u)}{u} = 1.

    Applying this identity: limu02sin(u)u=2limu0sin(u)u=2×1=2\lim_{u \to 0} \frac{2\sin(u)}{u} = 2 \lim_{u \to 0} \frac{\sin(u)}{u} = 2 \times 1 = 2

Conclusion

Thus, the limit is: limx0sin(2x)x=2\lim_{x \to 0} \frac{\sin(2x)}{x} = 2

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

Here are some related questions to further your understanding:

  1. What is the limit of limx0sin(3x)x\lim_{x \to 0} \frac{\sin(3x)}{x}?
  2. How does the substitution method help in evaluating limits involving trigonometric functions?
  3. Can we apply L'Hopital's Rule to solve limx0sin(2x)x\lim_{x \to 0} \frac{\sin(2x)}{x}? What would be the result?
  4. What are some other common limits involving trigonometric functions?
  5. How would the solution change if the function was limx0tan(2x)x\lim_{x \to 0} \frac{\tan(2x)}{x}?

Tip: Always consider using trigonometric identities and substitution when simplifying limits involving trigonometric functions.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometric Functions
Substitution

Formulas

Limit properties
Trigonometric identities

Theorems

Sine limit identity

Suitable Grade Level

Advanced High School