# How do you find the horizontal asymptote. y = (1 - x)/(1 + x)?

$y = \frac{1 + x - 2 x}{1 + x} = 1 - \frac{2 x}{1 + x}$
${\lim}_{x \to \infty} y = - 1$
Hence the horizontal asymptote is $y = - 1$