Question

Which of the following rational functions is graphed below?

Answer 1

Answer: Choice C $f(x) = \frac{1}{x(x+4)}$

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Explanation:

The vertical asymptotes are the red dashed lines. They are x = -4 and x = 0. Think of them as electric fences that the graph cannot touch or cross. The curve can only get closer and closer.

The vertical asymptote is due to a division by zero error.

When x = 0, the denominator x(x+4) turns into 0 since

x(x+4) = 0(0+4) = 0*4 = 0

Similarly, when x = -4, the denominator is also zero

x(x+4) = -4(-4+4) = -4*0 = 0

So if x = -4 or x = 0, then we have a division by zero error and that's what produces the vertical asymptotes at those locations shown on the graph.

This is why the answer is choice C. $f(x) = \frac{1}{x(x+4)}$