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Qiuyun TMUA Simulation Test Paper 2 · Q14

Paper 2Logic & proofFunctions & graphs

Here is a true statement:

A function f:M→Mf:M\to M is said to be a contraction mapping if there exists a number C<1C<1 such that ∣f(x)−f(y)∣≤C×∣x−y∣|f(x)-f(y)|\le C\times|x-y| for all x,y∈Mx,y\in M.

Which of the following statements must be true?

AIf a function f:M→Mf:M\to M is not a contraction mapping, then for any C≥1C\ge1, there exist some x,y∈Mx,y\in M such that ∣f(x)−f(y)∣>C×∣x−y∣|f(x)-f(y)|>C\times|x-y|.
BIf a function f:M→Mf:M\to M is not a contraction mapping, then for any C≥1C\ge1, we have ∣f(x)−f(y)∣≤C×∣x−y∣|f(x)-f(y)|\le C\times|x-y| for all x,y∈Mx,y\in M.
CIf a function f:M→Mf:M\to M is not a contraction mapping, then for any C<1C<1, there exist some x,y∈Mx,y\in M such that ∣f(x)−f(y)∣>C×∣x−y∣|f(x)-f(y)|>C\times|x-y|.
DIf a function f:M→Mf:M\to M is not a contraction mapping, then for any C<1C<1, we have ∣f(x)−f(y)∣≤C×∣x−y∣|f(x)-f(y)|\le C\times|x-y| for all x,y∈Mx,y\in M.
EIf there exists a number C≥1C\ge1 such that ∣f(x)−f(y)∣>C×∣x−y∣|f(x)-f(y)|>C\times|x-y| for all x,y∈Mx,y\in M, then this function f:M→Mf:M\to M is not a contraction mapping.
FIf there exists a number C≥1C\ge1 such that ∣f(x)−f(y)∣≤C×∣x−y∣|f(x)-f(y)|\le C\times|x-y| for all x,y∈Mx,y\in M, then this function f:M→Mf:M\to M is not a contraction mapping.

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