What's uner the sqrt sign is >=0
So,
(13x)/(x^2-1)>=0
(13x)/((x+1)(x-1))>=0
Let f(x)=(13x)/((x+1)(x-1))
We can build a sign chart
color(white)(aaaa)xcolor(white)(aaaa)-oocolor(white)(aaaaa)-1color(white)(aaaaa)0color(white)(aaaaaaa)+1color(white)(aaaa)+oo
color(white)(aaaa)x+1color(white)(aaaa)-color(white)(aaaa)||color(white)(aa)+color(white)(aaaa)+color(white)(aaaa)||color(white)(aa)+
color(white)(aaaa)xcolor(white)(aaaaaaa)-color(white)(aaaa)||color(white)(aa)-color(white)(aaaa)+color(white)(aaaa)||color(white)(aa)+
color(white)(aaaa)x-1color(white)(aaaa)-color(white)(aaaa)||color(white)(aa)-color(white)(aaaa)-color(white)(aaaa)||color(white)(aa)+
color(white)(aaaa)f(x)color(white)(aaaaa)-color(white)(aaaa)||color(white)(aa)+color(white)(aaaa)-color(white)(aaaa)||color(white)(aa)+
Therefore,
f(x)>=0 when x in (-1,0] uu (+1,+oo)
The domain is x in (-1,0] uu (+1,+oo)
Let,
y=sqrt((13x)/(x^2-1))
When x=-1, =>, y=+oo
When x=0, =>, y=0
The range is y in [0,+oo)