For the given function \(f\), evaluate the limit and justify your answer.

(a)
\(f(x)=x\)
\[ \lim _{x\to 7}f(x) = \answer {7} \]
Justification:
\(f\) is continuous at \(a=7\), which implies that \(\lim _{x\to 7}f(x)=f(\answer {7})=\answer {7}\).

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(b)
\(f(x)=x^3\)
\[ \lim _{x\to -2}f(x) = \answer {-8} \]
Justification:
\(f\) is continuous at \(a=-2\), which implies that
\(\lim _{x\to -2}f(x)=f\Bigl (\answer { -2} \Bigr )=\Bigl (\answer {-2 }\Bigr )^3=\answer {-8}\).

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(c)
\(f(x)=e^{x}\)
\[ \lim _{x\to 0}f(x) = \answer {1} \]
Justification:
\(f\) is continuous at \(a=0\), which implies that
\(\lim _{x\to 0}f(x)=f\Bigl (\answer {0}\Bigr )=e^{\answer {0}}=\answer {1}\).

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(d)
\(f(x)=\ln {x}\)
\[ \lim _{x\to e^{4}}f(x) = \answer {4} \]
Justification:
\(f\) is continuous at \(a=e^{4}\), which implies that
\(\lim _{x\to e^{4}}f(x)=f\Bigl (\answer {e^{4}}\Bigr )=\ln {\Bigl (\answer {e^{4}}\Bigr )}=\answer {4}\).

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(e)
\(f(x)=\cos {x}\)
\[ \lim _{x\to \frac {2\pi }{3}}f(x) = \answer {-\frac {1}{2}} \]
Justification:
\(f\) is continuous at \(a= \frac {2\pi }{3}\), which implies that
\(\lim _{x\to \frac {2\pi }{3}}f(x)=f\Bigl (\answer { \frac {2\pi }{3}}\Bigr )=\cos {\Bigl (\answer { \frac {2\pi }{3}}\Bigr )}=\answer {-\frac {1}{2}}\).