Recent questions and answers in Analysis

0 0 votes
1 1 answer
134
134 views
Prove or disprove each of the statements below.Let $f: \mathbb{R}^{2} \longrightarrow \mathbb{R}$ be a continuous function that takes both positive and negative values. T...
1 1 vote
1 1 answer
257
257 views
Let $f:[0,1] \rightarrow \mathbb{R}$ be such that\[f(x)=\left\{\begin{array}{ll}\frac{1}{2^{n}}, & \text { if } x=\frac{p}{2^{n}}, \text { where } p \text { is an odd int...
1 1 vote
1 1 answer
249
249 views
Let $x_{n}=\left(1-\frac{1}{\sqrt{n}}\right)^{n} \exp \left(n^{\frac{1}{4}}\right)$. Which of the following statements is correct?$\displaystyle \lim _{n \rightarrow \inf...
0 0 votes
1 1 answer
208
208 views
What is the number of functions $f: \mathbb{R} \backslash\{0,1\} \rightarrow \mathbb{R} \backslash\{0,1\}$ such that $|f(x)-f(y)|=|x-y|$ for all $x, y \in \mathbb{R} \bac...
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0 0 answers
253
253 views
What is the domain of the following real valued function?\[f(x)=\log _{2}\left(x^{2}-5 x+6\right).\]$(-\infty, 2)$$(3, \infty)$$(-\infty, 2) \cup(3, \infty)$$(-\infty, \i...
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160
160 views
Define a set $S$ of real polynomials as follows:\[S=\{p \in \mathbb{R}[x] \mid p \text { is not constant, }|p(0)|<1\}\]For $p$ in $S$, define\[U_{p}=\{x \in \mathbb{R}| |...
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151
151 views
Let $\left\{q_{n}\right\}_{n=1}^{\infty}$ be an enumeration of the rationals. In other words, $\mathbb{Q}=\left\{q_{n} \mid n \in \mathbb{N} \backslash\{0\}\right\}$, and...
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198
198 views
Let $S$ be the set of functions $f:(0,1) \rightarrow \mathbb{R}$ with the property that there is a sequence $\left\{f_{n}\right\}_{n=1}^{\infty}$ of functions that conver...
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0 0 answers
165
165 views
For a real valued function $f:[0,1] \mapsto \mathbb{R}$, let $\omega_{f}:[0,1] \mapsto \mathbb{R}$ be the $oscillation$ of $f$ defined by\[\omega_{f}(t):=\sup _{|x-y| \le...
1 1 vote
0 0 answers
207
207 views
Let $C([0,1], \mathbb{R})$ be the set of continuous functions from $[0,1]$ to $\mathbb{R}$, equipped with the metric $d$ given by\[d\left(f_{1}, f_{2}\right)=\sup _{x \in...
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0 0 answers
140
140 views
There are uncountably many continuous functions $\mathbb{Q} \rightarrow\{0,1\}$.
1 1 vote
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155
155 views
Let $f: \mathbb{R} \rightarrow \mathbb{R}$ be a continuously differentiable function. Suppose there exists $C \in \mathbb{R}$ such that $f$ is injective on ( $C, \infty$ ...
1 1 vote
0 0 answers
215
215 views
If $f, g:[0,1] \rightarrow \mathbb{R}$ are continuous and $f \cdot g=0$, then one of $f$ or $g$ is zero on an open subset of $[0,1]$.
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