# Algebra

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What is the difference between domain and range? Describe a real life situation that could be modeled by a function?

I think I understand domain and range. Domain is the x axis and range is the y axis correct?
I need help with applying it to real life.

Thank you.

• Algebra -

Close. The domain is all the possible x values and the range is all the possible y values. *I'm sure there is a more general way of phrasing it but my english sucks sorry.*

Lets use an example y = x.
There is no restrictions such as undefines so the domain and range are all real values.

y = sqrt(x). In this case x cannot be negative. The lowest value of x that will still give us a real number is 0 and the is no max so the domain is 0 to infinity. The range cannot be lower than 0 because there is no x value that will return a number lower than 0. The max is infinity because as x goes to infinity so does y(if you don't understand what this means please ask).

A function can be very simple. Like..

The price of one apple is 10 cents. Jack wants to buy x number of apples What is the price of x apples?

Err it's crude example but I can't think of anything else right now >.<.

Just a note, one property of a function is that every x value has one and only one y value. So as long as a real life situation does not have two outcomes, it can(I believe) be model as a function.

Best of luck I hope I helped >.<"

• Algebra -

Yes, thank you!

• Algebra -