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Proof, EXT2 EQ-Bank 21

Prove that  \(\lim\limits_{x \to 0}x^2\, \sin \left(\dfrac{1}{x}\right)=0\).   (2 marks)

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\(-1 \leqslant \sin \left(\dfrac{1}{x}\right) \leqslant 1\)

\(-x^2 \leqslant x^2\, \sin \left(\dfrac{1}{x}\right) \leqslant x^2\)
 

\(\text{By squeeze theorem:}\)

\(\text{Since} \ \ \lim\limits_{x \to 0}-x^2=0\ \ \text{and}\ \ \lim\limits _{x \rightarrow 0} x^2=0\)

\(\Rightarrow \lim\limits _{x \rightarrow 0} x^2\, \sin \left(\dfrac{1}{x}\right)=0\)

Show Worked Solution

\(-1 \leqslant \sin \left(\dfrac{1}{x}\right) \leqslant 1\)

\(-x^2 \leqslant x^2\, \sin \left(\dfrac{1}{x}\right) \leqslant x^2\)
 

\(\text{By squeeze theorem:}\)

\(\text{Since} \ \ \lim\limits_{x \to 0}-x^2=0\ \ \text{and}\ \ \lim\limits _{x \rightarrow 0} x^2=0\)

\(\Rightarrow \lim\limits _{x \rightarrow 0} x^2\, \sin \left(\dfrac{1}{x}\right)=0\)

Filed Under: Inequalities Tagged With: Band 4, smc-7423-75-Squeeze Theorem

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