How do you find the domain and range of sqrt((13x)/((x^2)-1)?

1 Answer
May 29, 2017

The domain is x in (-1,0] uu (+1,+oo)
The range is y in [0,+oo)

Explanation:

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)