SOLUTION: Is there an easier way to phrase the instructions in book? I am not understanding the examples and phases in the book.After finding the domain and range, just how can you tell if i

Question 141027This question is from textbook Intermediate Alebra A Graphing Approach
: Is there an easier way to phrase the instructions in book? I am not understanding the examples and phases in the book.After finding the domain and range, just how can you tell if it's a function or not. This question is from textbook Intermediate Alebra A Graphing Approach

Found 2 solutions by vleith, rapaljer:
Answer by vleith(2983) (Show Source): You can put this solution on YOUR website!
I do not have your book, but if you have found the domain and the range, then you can tell if the expression is a function by using the 'vertical line rule'. On a plot of the graph, if any vetical line intersects the graph in two places, that graph is not a function.
In words, if any one value in the domain maps to more than one value in the range, it is not a function.
Basically, a function uniquely maps a single value if X to a single value of Y. You can map many Xs to the same Y, but no single X can be mapped to two different Ys.
I hope that helps
Answer by rapaljer(4671) (Show Source): You can put this solution on YOUR website!
You might want to see my explanations of the topics. For additional explanation on the topic of Domain and Range, see my own website by clicking on my tutor name "rapaljer" anywhere in algebra.com. Take the third link on my homepage which is "Math in Living Color", click on "College Algebra" and look for Chapter 2, Section 2.07 Functions, Domain, and Range. This is a section of problems that I have solved in LIVING COLOR, with an explanation written for folks who didn't get math the first time!!

As to your specific question, "How do you tell if something is a function or not?", there are two perspectives. First to look at the graph of the function. If you can graph it (and if you have a graphing calculator, this can be a HUGE help for you!!), use what we call the "vertical line test". If ANY vertical line intersects the graph in more than one point, then it is NOT a function.

More specifically, if you have an equation of an equation in x and y, if this equation has a y= + or -, then it is NOT a function! Secondly, if the equation has a y^2, y^4, y^(even) power, then it is NOT a function. However, if you can solve for y, and write this in the form of "y=______", then it IS a function. Maybe this will help in most problems. Do you have specific equations in mind?

R^2

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