Domain and vertical asymptotes
Consider the function This function will be analyzed to build a complete curve sketch.
Factor the numerator and denominator of completely. Using this factorization, state the domain of and identify all vertical asymptotes of .
Hint
Factor as and as . A vertical asymptote occurs where the denominator is zero but the numerator is not zero at that same point (after cancellation, if any).
Step-by-step solution
Factor: numerator , denominator . So . There are no common factors between numerator and denominator, so no holes occur.
The denominator is zero at , and the numerator is nonzero at each of these points, so all three are vertical asymptotes. The domain is all real numbers except , i.e. .
Intercepts
Find all -intercepts and the -intercept of , or explain why one does not exist.
Hint
For x-intercepts, set the numerator equal to zero (checking these points are in the domain). For the y-intercept, evaluate if it exists.
Step-by-step solution
Set the numerator equal to zero: gives and . Both values are in the domain (they don't make the denominator zero), so the -intercepts are and .
For the -intercept, we need , but is not in the domain since the denominator vanishes there. Therefore there is no -intercept.
Horizontal asymptote
Determine the horizontal asymptote (if any) of by evaluating .
Hint
Compare the degree of the numerator (2) to the degree of the denominator (3), or divide numerator and denominator by the highest power of in the denominator.
Step-by-step solution
Divide numerator and denominator by : . As , every term with in the denominator goes to 0, leaving .
Since the degree of the numerator (2) is less than the degree of the denominator (3), the limit as is 0 in both directions, so is a horizontal asymptote.
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