Math Problem Statement

Nilai dari lim_{x→−2} \frac{(x^2-4) tan(x+2)}{sin^2(x+2)} adalah ...

Solution

The given limit problem is:

limx2(x24)tan(x+2)sin2(x+2)\lim_{x \to -2} \frac{(x^2 - 4) \cdot \tan(x+2)}{\sin^2(x+2)}

Step 1: Factorize x24x^2 - 4

The expression x24x^2 - 4 is a difference of squares, so it can be factorized as:

x24=(x2)(x+2)x^2 - 4 = (x - 2)(x + 2)

Thus, the limit becomes:

limx2(x2)(x+2)tan(x+2)sin2(x+2)\lim_{x \to -2} \frac{(x - 2)(x + 2) \cdot \tan(x+2)}{\sin^2(x+2)}

Step 2: Substitution

Let u=x+2u = x + 2, which implies that as x2x \to -2, u0u \to 0. Substituting uu into the limit:

limu0(u4)tan(u)sin2(u)\lim_{u \to 0} \frac{(u - 4) \cdot \tan(u)}{\sin^2(u)}

Step 3: Analyze Limit Behavior

  • As u0u \to 0, tan(u)u\tan(u) \approx u and sin(u)u\sin(u) \approx u (from small angle approximations).
  • Using these approximations:

limu0uuu2=limu01=1\lim_{u \to 0} \frac{u \cdot u}{u^2} = \lim_{u \to 0} 1 = 1

Therefore, the limit of the entire expression is:

4\boxed{4}

Would you like further explanation or details?


Here are five related questions to expand your understanding:

  1. How do you handle limits involving trigonometric functions?
  2. What is the small angle approximation for trigonometric functions like sine and tangent?
  3. How does L'Hôpital's Rule apply to indeterminate forms in limits?
  4. What is the general approach to solving limits involving factorization?
  5. Can you solve limits without using trigonometric approximations?

Tip: For limits involving trigonometric functions near 0, small angle approximations such as sin(x)x\sin(x) \approx x and tan(x)x\tan(x) \approx x are very useful.

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Math Problem Analysis

Mathematical Concepts

Limits
Trigonometric Functions
Factorization
Small Angle Approximation

Formulas

Difference of squares: x^2 - 4 = (x - 2)(x + 2)
Small angle approximations: \sin(x) \approx x, \tan(x) \approx x for small x

Theorems

Limit approximation using small angle trigonometric approximations

Suitable Grade Level

Grades 10-12