<|system|>
How many vertical asymptotes does the equation $y=\frac{x-1}{x^2+6x-7}$ have?</s>.
<|user|>
Can you answer based on context?
<|assistant|>
By factoring the denominator, the equation becomes $\frac{x-1}{(x-1)(x+7)}$. So the denominator equals $0$ when $x=1$ and $x=-7$. However, since the term $x-1$ also exists in the numerator and is of the same degree as in the denominator, $x=1$ is not a vertical asymptote. Therefore, the equation has only $1$ vertical asymptote at $x=-7$.