Math Is Fun Forum

Hannibal lecter

Member

Registered: 2016-02-11

Posts: 392

what is the domain of the following equation ...

what is the domain of  y = sqrt{t^2-16}

I saw this answer :-
The value of f(t) is real provided t2 −16 ≥ 0 or t2 ≥ 16. This occurs when either t ≥ 4, or t ≤−4

I mean how to write it as interval notation?
is it :
[-4,-∞) or [4,∞)
am I right?

Last edited by Hannibal lecter (2019-08-01 14:54:16)

---

Wisdom is a tree which grows in the heart and fruits on the tongue

Bob

Administrator

Registered: 2010-06-20

Posts: 10,140

Re: what is the domain of the following equation ...

hi Hannibal lecter

Yes, that's ok except write (-∞, -4] so the interval runs from left to right.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

Hannibal lecter

Member

Registered: 2016-02-11

Posts: 392

Re: what is the domain of the following equation ...

but you told me in previous post that I can swap intervals
http://www.mathisfunforum.com/viewtopic.php?pid=410328#p410328
so can I write [-4,-∞) or this will be wrong?

---

Wisdom is a tree which grows in the heart and fruits on the tongue

Bob

Administrator

Registered: 2010-06-20

Posts: 10,140

Re: what is the domain of the following equation ...

It's usual to put the lower amount first.

See https://www.mathsisfun.com/sets/intervals.html

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob