Practice Squeeze Theorem in Math

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

If g(x)≀f(x)≀h(x)g(x) \leq f(x) \leq h(x) near x=ax = a, and lim⁑xβ†’ag(x)=lim⁑xβ†’ah(x)=L\lim_{x \to a} g(x) = \lim_{x \to a} h(x) = L, then lim⁑xβ†’af(x)=L\lim_{x \to a} f(x) = L.

If ff is squeezed between two functions that both approach the same value LL, then ff has no choiceβ€”it must also approach LL. Like being caught between two walls closing in to the same point.

Showing a random 20 of 50 problems.

Example 1

medium
Find lim⁑xβ†’0sin⁑(5x)5x\lim_{x\to 0} \dfrac{\sin(5x)}{5x}.

Example 2

hard
Find lim⁑xβ†’0sin⁑(x)cos⁑(1/x)\lim_{x\to 0} \sin(x)\cos(1/x).

Example 3

hard
Find lim⁑xβ†’0+xln⁑x\lim_{x\to 0^+} x\ln x using a squeeze idea (granting lim⁑xβ†’0+ln⁑x1/x=0\lim_{x\to 0^+}\dfrac{\ln x}{1/\sqrt x}=0).

Example 4

medium
Evaluate lim⁑xβ†’0x4cos⁑(1/x)\lim_{x\to 0} x^4 \cos(1/x).

Example 5

easy
Use the squeeze theorem to find lim⁑xβ†’0x2sin⁑ ⁣(1x)\displaystyle\lim_{x \to 0} x^2 \sin\!\left(\frac{1}{x}\right).

Example 6

medium
Use ∣1βˆ’cos⁑xβˆ£β‰€x22|1-\cos x|\le \dfrac{x^2}{2} to find lim⁑xβ†’01βˆ’cos⁑xx2\lim_{x\to 0} \dfrac{1-\cos x}{x^2} is bounded above by what?

Example 7

challenge
Show that if ∣f(x)βˆ’Lβˆ£β‰€M∣xβˆ’a∣p|f(x)-L|\le M|x-a|^p for some M>0,p>0M>0, p>0 and all xx near aa, then lim⁑xβ†’af(x)=L\lim_{x\to a} f(x)=L.

Example 8

medium
Evaluate lim⁑nβ†’βˆž(βˆ’1)nn\lim_{n\to\infty} \dfrac{(-1)^n}{n}.

Example 9

challenge
Given ∣f(x)βˆ’3βˆ£β‰€βˆ£xβˆ’2∣|f(x) - 3| \leq |x - 2| for all xx, prove lim⁑xβ†’2f(x)=3\lim_{x\to2} f(x) = 3.

Example 10

easy
Find lim⁑xβ†’0xcos⁑ ⁣(1x)\displaystyle\lim_{x \to 0} x\cos\!\left(\frac{1}{x}\right).

Example 11

hard
Find lim⁑nβ†’βˆž1+2+β‹―+⌊nsin⁑nβŒ‹n2\lim_{n\to\infty} \dfrac{1+2+\cdots+\lfloor n\sin n\rfloor}{n^2} bounded in absolute value.

Example 12

medium
Show that lim⁑nβ†’βˆžsin⁑nn=0\displaystyle\lim_{n\to\infty} \frac{\sin n}{n} = 0.

Example 13

medium
Evaluate lim⁑xβ†’0x2⌊1/xβŒ‹\lim_{x\to0} x^2 \lfloor 1/x \rfloor where βŒŠβ‹…βŒ‹\lfloor\cdot\rfloor is the floor.

Example 14

easy
Given βˆ’x2≀f(x)≀x2-x^2\le f(x)\le x^2 near 00, find lim⁑xβ†’0f(x)\lim_{x\to 0} f(x).

Example 15

easy
Evaluate lim⁑xβ†’0x2sin⁑ ⁣(1x)\lim_{x\to0} x^2 \sin\!\left(\frac{1}{x}\right).

Example 16

medium
Find lim⁑xβ†’βˆž2+cos⁑xx\lim_{x\to\infty} \frac{2 + \cos x}{x}.

Example 17

medium
Given cos⁑x≀sin⁑xx≀1\cos x \leq \frac{\sin x}{x} \leq 1 near 0, find lim⁑xβ†’0sin⁑xx\lim_{x\to0} \frac{\sin x}{x}.

Example 18

challenge
Prove lim⁑xβ†’0x⌊1/xβŒ‹=1\lim_{x\to0} x \lfloor 1/x \rfloor = 1 does not follow from naive bounds; find the correct limit.

Example 19

challenge
Use the squeeze theorem to find lim⁑nβ†’βˆž2n+3nn\lim_{n\to\infty} \sqrt[n]{2^n + 3^n}.

Example 20

medium
Find lim⁑xβ†’01βˆ’cos⁑xx\lim_{x\to0} \frac{1 - \cos x}{x} using 0≀1βˆ’cos⁑x≀x220 \leq 1 - \cos x \leq \frac{x^2}{2}.