Evaluate: lim(x->0) (sin(5x) - sin(3x)) / (sin(x)).

Answer: 2

Step-by-step solution

Step 1: Apply L'Hôpital's Rule

First, we check the limit by direct substitution. Substituting x=0x=0 into the expression gives sin⁡(0)−sin⁡(0)sin⁡(0)=00\frac{\sin(0) - \sin(0)}{\sin(0)} = \frac{0}{0}, which is an indeterminate form. Therefore, we can apply L'Hôpital's Rule, which states that if lim⁡x→cf(x)g(x)\lim_{x\to c} \frac{f(x)}{g(x)} is of the form 00\frac{0}{0} or ∞∞\frac{\infty}{\infty}, then lim⁡x→cf(x)g(x)=lim⁡x→cf′(x)g′(x)\lim_{x\to c} \frac{f(x)}{g(x)} = \lim_{x\to c} \frac{f'(x)}{g'(x)}.

Step 2: Differentiate numerator and denominator

We differentiate the numerator and the denominator with respect to x. The derivative of sin⁡(ax)\sin(ax) is a cos⁡(ax)\cos(ax), so ddx(sin⁡(5x))=5cos⁡(5x)\frac{d}{dx}(\sin(5x)) = 5\cos(5x) and ddx(sin⁡(3x))=3cos⁡(3x)\frac{d}{dx}(\sin(3x)) = 3\cos(3x). The derivative of sin⁡(x)\sin(x) is cos⁡(x)\cos(x).

Step 3: Substitute x=0x=0

Now that we have differentiated the numerator and the denominator, we can substitute x=0x=0 into the new expression. We know that cos⁡(0)=1\cos(0) = 1.

Step 4: Calculate the final value

Substituting cos⁡(0)=1\cos(0) = 1 into the expression, we get 5(1)−3(1)1\frac{5(1) - 3(1)}{1} = 5−31\frac{5 - 3}{1} = 2. This is the final value of the limit.

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