Practice Local vs Global Behavior in Math

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

Quick Recap

Local behavior describes a function's properties near a specific point; global behavior describes its overall properties across the entire domain or as inputs grow without bound.

Local is "zoom in on one spot"; global is "zoom out to see the whole picture." Near x=0x = 0, sinโก(x)โ‰ˆx\sin(x) \approx x (local linear approximation), but globally it oscillates forever.

Showing a random 20 of 50 problems.

Example 1

medium
Use the local approximation lnโก(1+x)โ‰ˆx\ln(1 + x) \approx x near x=0x = 0 to estimate lnโก(1.05)\ln(1.05).

Example 2

easy
Near x=0x = 0, cosโก(x)โ‰ˆ1โˆ’x22\cos(x) \approx 1 - \tfrac{x^2}{2}. Is this a local or global statement?

Example 3

easy
For f(x)=sinโก(x)f(x) = \sin(x), what are the global maximum and minimum values?

Example 4

easy
For f(x)=x3โˆ’3xf(x)=x^3-3x, describe: (a) local behavior near x=0x=0 using the linear approximation, and (b) global behavior as xโ†’ยฑโˆžx\to\pm\infty.

Example 5

hard
For f(x)=xeโˆ’xf(x) = xe^{-x} on [0,โˆž)[0, \infty), find the global maximum.

Example 6

hard
A function ff satisfies f(0)=10f(0) = 10 and has local minima at x=1x = 1 and x=5x = 5 with values f(1)=2f(1) = 2 and f(5)=โˆ’3f(5) = -3. What is the global minimum on R\mathbb{R}, assuming end behavior f(x)โ†’+โˆžf(x) \to +\infty as xโ†’ยฑโˆžx \to \pm \infty?

Example 7

medium
f(x)=sinโกxf(x) = \sin x has period 2ฯ€2\pi. Describe its local behavior near x=0x = 0 versus its global behavior over all reals.

Example 8

easy
f(x)=โˆ’x2+10f(x) = -x^2 + 10 has a peak at x=0x = 0 with value 10. Is this peak a local maximum, a global maximum, or both?

Example 9

easy
Zooming way in on the graph of f(x)=x2f(x) = x^2 at x=2x = 2, it looks almost like a straight line. What is this called?

Example 10

easy
Does knowing f(0)=3f(0) = 3 tell you the global maximum of ff?

Example 11

medium
A model fits data well for 0โ‰คxโ‰ค100 \le x \le 10 but predicts a negative population at x=50x = 50. Is the failure a local or global (extrapolation) problem, and what is the lesson?

Example 12

easy
True or false: a local maximum is always the global maximum.

Example 13

hard
On [1,4][1, 4], find the global max and min of f(x)=x+4xf(x) = x + \dfrac{4}{x}.

Example 14

challenge
A function is locally increasing at every point in (0,10)(0, 10) yet you are told it is NOT globally increasing on the reals. Construct a simple example and explain the apparent paradox.

Example 15

easy
Which is global: 'slope is โˆ’2-2 at x=3x = 3' or 'function approaches a horizontal asymptote y=0y = 0'?

Example 16

medium
On [โˆ’3,3][-3, 3], find the global max and min of f(x)=x3โˆ’12xf(x) = x^3 - 12x.

Example 17

medium
Near x=0x = 0, f(x)=exโ‰ˆ1+xf(x) = e^x \approx 1 + x. Use the local approximation to estimate e0.1e^{0.1}, and explain why it fails for x=5x = 5.

Example 18

medium
f(x)=x4โˆ’4x2f(x) = x^4 - 4x^2 (slope 4x3โˆ’8x4x^3 - 8x). It has critical points at x=0,ยฑ2x = 0, \pm\sqrt{2}. Given f(0)=0f(0)=0 and f(ยฑ2)=โˆ’4f(\pm\sqrt2) = -4, identify the global minimum.

Example 19

easy
On the closed interval [0,4][0, 4], f(x)=xf(x) = x has a global maximum of what value?

Example 20

easy
Does f(x)=exf(x) = e^x have a global maximum on R\mathbb{R}?