See also the
Browse High School Functions
Stars indicate particularly interesting answers or
good places to begin browsing.
Selected answers to common questions:
Composition of functions.
Domain and range.
Inverse of a function.
- Function Its Own Inverse [01/02/1998]
Show that f(x) = X/X-1 is its own inverse.
- Functions [11/12/1994]
I'm a first year algebra student having difficulty learning about
functions. Exactly how do they work?
- Functions and Equations [02/10/2001]
When is an equation also a function? How do you recognize a function?
- Functions and Function Tables [05/11/1999]
I don't understand functions and function tables. Can you help me?
- Functions and Inverses [05/29/2002]
Find sets A, B, and C, and functions f:A->B and g:B->C, such that
(g o f) is both injective and surjective, but f is not surjective
and g is not injective.
- Functions: Domain, Range, and Piecewise [08/31/1998]
What are piecewise functions? What are open and closed points? How do you
figure out the domain and range of a function without graphing it on a
- Functions of a Complex Variable [10/05/2002]
Show that w=f(z*), where z*=x-iy and f is a differentiable function,
is not an analytic function of z.
- Functions of Imaginary Numbers [7/31/1996]
Does (ln i) itself exist? Where does e^iA = cos A + i sin A come from?
- Functions O(k) and Omega(k) [01/20/2001]
Please explain the difference between the functions O(k) and Omega(k).
- Functions Possible for a Symmetric, Asymptotic Graph [02/02/2013]
A student seeks an even function that would represent a graph with a horizontal
asymptote and symmetry around the y-axis. Doctor Peterson suggests considering
functions of the form 1/f(x) — or graphing f(x) by finding 1/y for every x.
- Functions that are their own inverses [02/28/1998]
Can a function ever be its own inverse?
- Functions: The Very Idea [04/08/2014]
A teen struggles to grasp what constitutes a function, and to reconcile the uniqueness
of two functions that differ in notationally or computationally trivial ways. Doctor
Peterson offers perspectives both abstract and concrete.
- Functions Without a Second Derivative [6/28/1996]
What are some examples of functions of a real variable whose derivatives
don't have derivatives?
- The Gamma Function and Its Derivative [05/26/1998]
Does n! = the integral from 0 to infinity of (x^n)(e^-x)dx hold true for
all real numbers? If so, can we find the derivative of n!?
- General Strategy for Questions on Functions [06/10/2004]
If the function f satisfies the equation f(x + y) = f(x) + f(y) for
every pair of real numbers x and y, what is (are) the possible
value(s) of f(0)?
- Graphing Absolute Values [07/03/2002]
I have a function, f(x), that I can graph, but I don't understand how
to graph |f(x)|.
- Graphing f(2x) and f(|x|) [09/03/2003]
Given f(x), how do you graph f(2x) and f(|x|)?
- Graphing Limits [09/12/2001]
I was hoping you could explain the concept of "limits" and how to read
them from graphs.
- Graphing Piecewise Functions [09/09/2001]
I do not understand how to graph piecewise functions.
- Graphing Polynomial Functions in Factored Form [07/07/2004]
When graphing polynomial functions, why do factors of even
multiplicity cause the graph to not cross the x-axis, while factors of
odd multiplicity cause it to cross?
- Graphing Rational Functions and Vertical Asymptotes [03/28/2008]
When working with rational functions such as y = (x-5)/(x-3), how do
you know if the graph curves up or down at the vertical asymptote?
- Graphing Reciprocal Functions [11/01/2001]
I know what a reciprocal is, but I don't know how to graph it.
- Graphing Sin and Cosine Functions [5/24/1996]
I really need some help in finding the graphs of the following
- Graphing the Absolute Value/Square Root of a Function [07/26/2002]
Can you illustrate and discuss how taking the absolute value or the
square root of a function affects the graph of the function?
- Graphing Two Functions With One Equation [10/21/2003]
I have a question on graphing functions. I am just wondering if it is
possible to use one equation to graph two functions?
- Graphing Two Functions with One Equation? [10/21/2003]
Suppose I have two functions, like y = sqrt(x) - 4 and y = sqrt(x) -
8. Is there a single equation that would produce the same graph as
the two functions graphed together?
- Graph of Circle as a Function [05/30/1998]
The graph of a circle is not a function because it fails the vertical
line test. How could you make it a function?
- Graphs of Inverse Functions [07/25/2002]
Explain why, if y=f(x) and y=g(x) are inverses, the graph of either
function is the graph of the other reflected across the line y=x.
- Graphs of Step Functions [11/29/2003]
Why do some graphs move in steps rather than smooth lines? What causes
- Graph with f(x) [10/17/2001]
Sketch the equations: y = f(x)+ 2; y = f(x-3); y = 2f(x).
- Greatest Integer Equation [08/06/2003]
I am trying to correctly interpret [[x]]^2 + [[y]]^2 = 1, where f(x)=
[[x]], is the Greatest Integer function.
- Greatest Integer Function [12/04/2002]
How can I explain greatest integer function to my home-schooled son?
- Greatest Integer Functions [09/27/1998]
Can you help me solve for the graph of [y]=[x], where  is the greatest
- The Heaviside Step Function [09/03/2003]
How can I construct a term that is zero when the input is below some
limit, but nonzero above it?
- How Are Functions and Expressions Related? [07/09/2004]
What is the relationship between a function and an expression? I
don't see any relationship, they are two completely different things.
- How to Evaluate 4!!!! [10/16/2003]
Our Calculus 2 teacher has challenged us to find the exact value for
4!!!!, but the number is too large to reasonably calculate by hand.
- How to Find the Range of a Function [02/25/1998]
How do you find the range of a function like g(x) = (x+1)/(x^2-1)?
- How to Solve Equations with No Analytic Solution Method [10/26/2005]
A discussion of solving equations that can't be solved analytically by
using iterative estimation methods including bisection, false
position, and Newton's method. The equation x(e^x) = 3 is used as an
- Hyperbolic Functions [06/27/1998]
What does the inverse of sinh or cosh mean?
- Hyperbolic Functions [10/14/1998]
Can you explain hyperbolic functions? How are they defined? How do you