Exercise · ZW-CONVERGENCE-IN-A-METRIC-SPACE-002 · ★☆☆ Basic
For \(x_n=1/n\) and \(\varepsilon=0.01\) in \(\mathbb{R}\), what is the smallest \(N\) with \(d(x_n,0)<\varepsilon\) for all \(n\ge N\)?
Choose one option.
Show answer
- B. \(101\)
Explanation
We need \(1/n<0.01\), that is \(n>100\). For \(n=100\) it equals \(0.01\), which is not smaller, so \(N=101\).
Review the concept: Convergence in a metric space
A sequence \((x_n)\) in a metric space \((X,d)\) converges to \(x\in X\) if, for every \(\varepsilon>0\), there is an index \(N\) from which \(x_n\) lies within distance \(\varepsilon\) of \(x\).
\[\forall\varepsilon>0\ \ \exists N:\ n\ge N\Rightarrow d(x_n,x)<\varepsilon\]
More practice problems: convergence in a metric space
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-001 In usual ℝ, what is the limit of x_n=1/n?
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-003 In Euclidean ℝ^2, to which point does x_n=(tfrac1n,tfracn+1n) converge?
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-004 In ℝ with the discrete metric, which of these sequences converges?
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-005 In usual ℝ, what happens with x_n=(-1)^n?
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-006 If x_n→ x and x_n→ y in a metric space, which argument proves x=y?
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-007 Let X=(0,1) with the usual distance and x_n=tfrac1n+1. Does it converge in X?
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-008 In ℝ^2 with d_∞(p,q)=max(|p_1-q_1|,|p_2-q_2|), let x_n=(tfrac1n,tfrac1n^2)→(0,0). What is the small…
- ZW-CONVERGENCE-IN-A-METRIC-SPACE-009 Which statement is equivalent to x_n→ x?
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