Domain? What?

Question

Quadratic Equations

I'm looking in my textbook and I see find the domain. What?
Then the answer is the symbol for All Real Numbers.

My question is how do I find the domain? and when and where would I put All Real Numbers?

Thank you ahead of time!

Answer 1

Your domain is all the possible x-values (or input) in a equation. To figure out the domain, you have to see the equation and it varies with different instances. For example, if there's a square root, the number under the square root will have to be a positive number greater than or equal to zero. If the input is under the square root, you will have to try to limit it so that the number under the square root is greater than or equal to zero. Addition and subtraction does not require an limits because they are limited by nothing. You can add anything together and get an answer.

As to where, it depends on the notations you are using (and there are quite a lot of different notations). Usually, you just put the symbol for All Real Numbers within the limits of x, or the input.

I hope this helps

Answer 2

Given a function y = f(x), the domain is all of the values possible for x. If not constrained to a certain interval such as -5 < x < 5, then the domain will be all the real numbers from - infinity to + infinity. In the case shown above, the domain all real numbers greater than -5 and less than + 5.

The range is the values that y can take on as a result of each x. The range is the smallest value of y to the largest value of y.

If y = F(x) = 1/x, the domain is all real numbers except zero. Division by zero is undefined.

If y=f(x) =1/[(x-1)(x-3), then x cannot = 1 or 3, else we would be dividing by zero. Hence the domain would be - infinity 3

Answer 3

The domain is the all the x values which are able to be used in the equation. Whether it is all real numbers, or just a few numbers.

Some examples:

2x...x can be anything...negative, positive, or zero...the domain is all real numbers.

1/x...x cannot be zero, you can never have a zero in the denominator...so, x is not equal to zero is your answer...be sure to use the 'not equal' symbol.

If you have an equation. 1+4x^2=5 Then you solve for x and find out what the possibilities are. If you know how to factor, then go ahead and do it...but this equation can be easily done in your head. The domain is x= -1, 1...because you want 5 as your answer...so if you use -1 or 1 then you'll get 1+4=5.

And there you have it...well, until you get to Calculus anyway. :P

Answer 4

If you have a function and it is defined on a set of number, this set is called domain.
The value the function become, for all the numbers in the domain is called the Range.

EX:

F(x)= 1/x; x≠0

You can easily see that the function is defined for all x in R\{0} that is the Domain
.....=========
the Range investigation:
x→+∞ => 0+ (from the +side)
x→ -∞ => 0- (from the - side )
x→ 0+ => f(x)→+∞
x→ 0- => f(x)→ -∞
You see the Range is {x in R\{0}}
========================

it was a little bit more than you have asked for, but try to learn the concepts

Regard from Denmark

Answer 5

Suppose we have a function y = f(x)
y is called the dependent variable and x the independent variable
In many situations the independent variable of th function is not free to be assigned any arbitrary value. Rather it must be constrained to lie in a set of values which are termed the domain of a function. The domain is simply the set of allowable values for the indpendent variable x. In practical applications the domain is often defined physical considerations. In the solutions of quadratic equations we might get a possible solution for length and time as negative which is physically not acceptable.
in your case the domain is the set of all real numbers R

Answer 6

The domain is the series of numbers used in your function... The sign for the real numbers is there just to tell you that the numbers in the series all have to be real numbers...

So... If your domain is the symbol for the Natural numbers, then all of them are in the set... Your function is a curve or line that will represent all of the results for any real number (your domain set,) and whatever calculation is in the function...

Answer 7

It looks like everyone is pretty much right although some are easier to understand than others.

I think the easiest way to do this is to solve three or four points for x and y. Put them on a graph.

Your line or curve should have endless answers in both directions (left or right)... you should be able to see that when you graph your equation. These x values are your Domain.

If they ask for Range (up and down) you should be able to look at your graph and see that too. Does it go up forever what about down?

Answer 8

Your domain is all real numbers, therefore your answer is all real numbers.

Answer 9

IF UR QUESTION IS FROM AN ALGEBRA BOOK I HAVE TO SAY THAT DOMAIN ARE THE Xs & THE RANGE R THE Ys IN THE ORDERED PAIRS