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Division by zero is not defined. This means that the denominator cannot be zero.
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.
This means that x=- 1 and x=1 are not included in the domain. Domain All real numbers except x=- 1 and x=1
Asymptotes can be vertical, horizontal, or oblique lines.
Once again, let's consider the given function.
f(x)=x^4-2/x^2-1
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 vertical asymptotes at x=- 1 and x=1.
To find the horizontal and oblique asymptotes we can use a set of rules. To properly use these rules, in the following m and n must be the highest degree of the numerator and the denominator.
| y=ax^m/bx^n | Asymptote | Asymptote Type |
|---|---|---|
| m | y=0 | Horizontal |
| m>n | None | None |
| m=n | y=a/b | Horizontal |
| m-n=1 | y= the quotient of the polynomials with no remainder | Oblique |
Let's look at the degrees of the numerator and denominator for our function. f(x)=x^4-2/x^2-1 We can see that the degree of the numerator is higher than the degree of the denominator. Therefore, there are no horizontal or oblique asymptotes.
The intercepts of the function are the points at which the graph intersects the axes.
f(x)= 0
LHS * (x^2-1)=RHS* (x^2-1)
LHS+2=RHS+2
Rearrange equation
sqrt(LHS)=sqrt(RHS)
Use a calculator
Let's make a table of values to graph the given function. Make sure to only use values included in the domain of the function.
| x | x^4-2/x^2-1 | f(x)=x^4-2/x^2-1 |
|---|---|---|
| - 2 | ( - 2)^4-2/( - 2)^2-1 | ≈ 4.67 |
| - 0.9 | ( - 0.9)^4-2/( - 0.9)^2-1 | ≈ 7 |
| - 0.5 | ( - 0.5)^4-2/( - 0.5)^2-1 | ≈ 2.58 |
| 0.5 | 0.5^4-2/0.5^2-1 | ≈ 2.58 |
| 0.9 | 0.9^4-2/0.9^2-1 | ≈ 7 |
| 2 | 2^4-2/2^2-1 | ≈ 4.67 |
Finally, let's plot and connect the points. Do not forget to draw the asymptotes and to plot the intercepts and holes, if any.