limx(sqrt(x^2+100)+x)
=lim100x/(sqrt(x^2+100)-x)
=lim100/(-sqrt(1+100/x^2)-1)
=-50 limx(sqrt(x^2+100)+x)
=lim100x/(sqrt(x^2+100)-x)
=lim100/(-sqrt(1+100/x^2)-1)
=-50