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Squeeze theorem applied to sin(x^2)/x

For all x≠0x \neq 0, note that ∣sin⁡(x2)x∣≤∣x∣\left|\dfrac{\sin(x^2)}{x}\right| \leq |x|.

Using the fact that −∣x∣≤sin⁡(x2)x≤∣x∣-|x| \leq \dfrac{\sin(x^2)}{x} \leq |x| for all x≠0x \neq 0, evaluate lim⁡x→0sin⁡(x2)x.\lim_{x \to 0} \frac{\sin(x^2)}{x}.

Hint

You are given the two bounding functions already. Find the limit of each bounding function as x→0x \to 0, then apply the Squeeze Theorem to conclude the limit of the function trapped between them.

Step-by-step solution

We are told that −∣x∣≤sin⁡(x2)x≤∣x∣-|x| \leq \dfrac{\sin(x^2)}{x} \leq |x| holds for all xx near 00 (with x≠0x \neq 0). This sets up the conditions for the Squeeze Theorem, since our function of interest is bounded between two simpler functions.

Compute the limits of the bounding functions: lim⁡x→0(−∣x∣)=0\lim_{x\to 0}(-|x|) = 0 and lim⁡x→0∣x∣=0\lim_{x\to 0}|x| = 0. Since both bounding functions approach the same value 00 as x→0x \to 0, the Squeeze Theorem guarantees that lim⁡x→0sin⁡(x2)x=0\lim_{x\to 0} \dfrac{\sin(x^2)}{x} = 0 as well.

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