# What do you mean by domain of a relation/function?

2
by keithhannah

2015-10-11T19:28:18+08:00
You use the value x for domain and y for range.when we say domain both x is 0      ex
x,y
(0,5) (0,2)
-both x is 0
If x is both 0 in a given expression, then it is only a relation (one is to many relation meaning O has more than one corresponding y values). How about for function? :-)
there are two types of function
i mean theres a function and non function.function is a pair of numbers that is not related to one another and not function has a relation to the same first entry.meaning its the x or domain
Please check your definition of function. . As for "two types of function", there are more than two (polynomial, cubic, linear, quadratic, trigonometric, etc.) the two you mentioned are not among them. And they are related to one another, that's why it's read as "function of"....
All functions are relation, but not all relations are functions. The issue with your answer is when you wrote is this "when we say domain, both x is 0". If both x is 0, then it's only a relation :-) You are partly correct with relation, but that does not answer the question posted. I encourage you to research or read more about it :-)
• Brainly User
2015-10-11T19:51:25+08:00
The domain of a relation or function are all the values of x (elements of reals numbers).  Each x-value has a corresponding y value.

Example:

f (x) = 2x + 3         Note:  f(x) is y-value for the given x.
f (4) = 2 (4) + 3
f (4) = 8 + 3
f (4) = 11

This means that if x = 4, then y = 11

The corresponding y-values is the range (elements of real numbers)

If all domain and range are elements of real numbers, then:
Domain = {x/x is an ∈ of Real Numbers}
Domain = (-∞ , +∞)

Range = {y/y is an ∈ or Real Numbers}
Range = (-∞ , +∞)