Question #e27b8

1 Answer
Oct 20, 2016

For x != 0x0, we have

x/sqrt(x^2+1) = x/sqrt(x^2(1+1/x^2))xx2+1=xx2(1+1x2)

= x/(sqrt(x^2)sqrt(1+1/x^2))=xx21+1x2

Since sqrt(x^2) = absxx2=|x|, we have

lim_(xrarroo) x/sqrt(x^2+1) =lim_(xrarroo)x/(xsqrt(1+1/x^2))

= lim_(xrarroo)1/sqrt(1+1/x^2)

= 1/sqrt(1+0) = 1

y=1 is a horizontal asymptote on the right.

On the left, we have x < 0, so sqrt(x^2) = -x and

lim_(xrarr-oo) x/sqrt(x^2+1) =lim_(xrarroo)x/(-xsqrt(1+1/x^2))

= lim_(xrarroo)-1/sqrt(1+1/x^2)

= -1/sqrt(1+0) = -1

y= -1 is a horizontal asymptote on the left.