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Exercises 1.4 Miscellaneous

Solve the following equations:

1.

\(\pi ^{x+1}=e\text{.}\)

Answer
\(\displaystyle x=\frac{1-\ln \pi }{\ln \pi }\text{.}\)
2.

\(2^{3^x}=10\text{.}\)

Answer
\(\displaystyle x=-\frac{\log \log 2}{\log 3}\text{.}\)
3.

Find the domain of the function \(\displaystyle f(x)=\frac{\ln (\ln (\ln x))}{x-3}+\sin x\text{.}\)

Answer
\((e,3)\cup (3,\infty )\text{.}\)

Solve the following problems:

4.

What is meant by saying that \(L\) is the limit of \(f(x)\) as \(x\) approaches \(a\text{?}\)

Answer
Give a definition of the limit.
5.

What is meant by saying that the function \(f(x)\) is continuous at \(x=a\text{?}\)

Answer
Give a definition of a function continuous at a point.
6.

State two properties that a continuous function \(f(x)\) can have, either of which guarantees the function is not differentiable at \(x=a\text{.}\) Draw an example for each.

Answer
A corner or a vertical tangent; \(y=|x|\text{;}\) \(\displaystyle y=x^{\frac{1}{3}}\text{.}\)