Help - domain and range (1 Viewer)

[raspb3rry]

Hi does anyone have any notes or pages from the 3unit textbooks which give good examples and explanations of how to do domain and range (functions) questions?

the textbook I'm using at school isn't very good, and I don't understand it. So is it possible if anyone scan some pages from their textbooks relating to that topic, with explanations and examples?

thanks~

 

[martin310015]

just think domain is the where the x values can be and for range where the y values can be.....

 

[kimmeh]

i dont think i know of any textbook that explains domain and range good. i remeber always getting it wrong in year 11, but then i finally understood it when i got to "curve sketching". maybe look there, it might trigger something in your brain

 

[iambored]

test values as well. you can never be too casreful. think logically - y>=0 is obviously not going to be -3. draw the graph if it's not hard to draw

i *think* the excel book might have done it ok.

 

[KeypadSDM]

Domain - Possible x values
Range - Possible y values

Usually, you do it where y = f(x), and this is the case I will describe.

For certain values of x, f(x) does not compute a value, or a real value. It is these values of x which are not part of the domain

For instance f(x) = Sqrt[x]
Since x < 0 give non-real values, x must be greater than or equal to 0.
:. Domain: x >= 0

Note that often f(x) does not cover all values from -oo to oo, and thus has a certain range of values which is covers.

As an example, f(x) = Sqrt[x] only covers the values greater than or equal to 0.

Thus domain is greater than or equal to 0.

:. y >= 0, where y = f(x)

Or something along those lines.

 

[raspb3rry]

This is a confusing topic lol. Thanks for all the tips and for your explanation KeypadSDM ^^'. I'll try staring at it for a while and hope I'll get something through my head~