Practice Limiting Cases in Math

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

Quick Recap

Extreme values of a parameter (approaching zero, infinity, or a critical threshold) used to check formulas and reveal simplified behavior.

What happens when things get really big, really small, or reach boundaries?

Showing a random 20 of 50 problems.

Example 1

medium
In the ideal gas law PV=nRT, what does pressure P approach as volume V→∞ at fixed T,n?

Example 2

medium
As x -> 0+, what does x*ln(x) approach? Use the dominance of x over ln(x).

Example 3

easy
What does the area formula A = pi r^2 give as r approaches 0?

Example 4

medium
A series sum is S = sum_{k=0}^{n} (1/2)^k. Find the limit of S as n -> infinity.

Example 5

easy
What does 1n2 approach as n→∞?

Example 6

easy
As x→0+, what does ln⁡x approach?

Example 7

easy
Check the formula for cylinder volume V=πr2h in the limit h→0. What should V approach?

Example 8

medium
A small-angle approximation uses sin(theta) approx theta for small theta. Use the limiting case to find the limit of sin(theta)/theta as theta -> 0.

Example 9

easy
Sanity check: a population model gives P = 100/(1 + e^(-t)). What does P approach as t -> infinity?

Example 10

challenge
Consider g(x) = x^x as x -> 0+ (x positive). Determine the limit and justify it.

Example 11

medium
Population grows as P(t)=P0ekt with k>0. What does P approach as t→∞?

Example 12

medium
Check the formula for resistors in parallel, R = (R1*R2)/(R1+R2), in the limit R2 -> infinity. What should R approach physically?

Example 13

challenge
For the Binomial probability with n large and p=λ/n, find the limit of P(X=k)=(nk)pk(1−p)n−k.

Example 14

easy
What does (1/2)^n approach as n grows large?

Example 15

easy
As n→∞, what does 2n+1n+3 approach?

Example 16

medium
As n→∞, what does nn approach?

Example 17

medium
For the partial sum Sn=1+1/2+1/4+…+1/2n−1, what does Sn approach as n→∞?

Example 18

easy
As x approaches infinity, what does e^(-x) approach?

Example 19

hard
A relativistic energy formula gives E=mc2/1−v2/c2. What does E approach as v→0?

Example 20

medium
Test the formula for the sum 1 + 2 + ... + n = n(n+1)/2 by checking the limiting case n = 1. Does it pass?