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Evaluate: $\lim_{x\rightarrow 0}\frac{\cos x – secx}{x^2}$
$\lim_{x\rightarrow 0}\frac{\cos x – secx}{x^2}$
= $\lim_{x\rightarrow 0}\frac{\cos x – \frac{1}{\cos x}}{x^2}$
= $\lim_{x\rightarrow 0}\frac{\cos^2x – 1}{x^2\cos x}$
= $\lim_{x\rightarrow 0}\frac{ – sin^2x}{x^2cosx}$
= $- \left(\lim_{x\rightarrow 0}\frac{\sin x}{x}\right)^2\lim_{x\rightarrow 0}\frac{1}{\cos x}$
=$ – (1)^2\ldotp 1$
= – 1
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