Limits and Continuity

Evaluate the following limits:

a) limx4x4x4\displaystyle \lim_{x \rightarrow 4} \frac{\sqrt{x} - \sqrt{4}}{x - 4}


b) limxx25x+134x4+3x21\displaystyle \lim_{x \rightarrow \infty} \frac{x^2 - 5x + 13}{\sqrt{4x^4 +3x - 21}}


c) limx0sin(3x)sin(5x)sin(x)sin(8x)\displaystyle \lim_{x \rightarrow 0} \frac{\sin(3x) \sin(5x)}{ \sin(x) \sin(8x)}
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