Division by zero is not defined. This means that the denominator cannot be zero.
Practice makes perfect
To graph the given rational function, we will find its domain, asymptotes, and intercepts. Then, we will find points using a table of values. Finally, we will plot and connect those points.
Domain
Consider the given function.
y=2x+3/x-5
Recall that division by zero is not defined. Therefore, the rational function is undefined where x-5=0.
x-5=0 ⇔ x=5
This means that x=5 is not included in the domain.
Domain
All real numbers except x=5
Once again, let's consider the given function.
y=2x+3/x-5
Note that we cannot cancel out common factors. Therefore, there are no holes. Also, if the real number a is not included in the domain, there is a vertical asymptote at x=a. In this case, we have a vertical asymptote at x=5.
Horizontal Asymptotes
To find the horizontal asymptotes, we can use a set of rules. To properly use these rules, in the following table m and n must be the highest degree of the numerator and denominator.
y=ax^m/bx^n
Asymptote
m
y=0
m>n
none
m=n
y=a/b
Now, consider the function one more time. Let's look at the degrees of the numerator and denominator for our function.
y=2x^1+3/x^1-5
We can see that the degree of the denominator is equal the degree of the numerator. Therefore, the line y=2 is a horizontal asymptote.
Intercepts
The intercepts of the function are the points at which the graph intersects the axes.
x-intercepts
The x-intercepts are the points where the graph intersects the x-axis. At these points, the value of the y-coordinate is zero. Let's substitute 0 for y in the given function and solve for x.
The y-intercept is the point where the graph intersects the y-axis. At this point, the value of the x-coordinate is zero.
Let's substitute 0 for x in the given function and solve for y.
