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Domain and Range?!

Hi,

So I'm doing Edexcel A2 Maths, and we are doing functions at the minute, but I just cannot understand the range and domain! Where do they come from and what are they for?! I was hoping someone could explain to me what they are in relatively simple terms.

Thank you!

Reply 1

B_9710

The domain is all the values you that you can put into the function. So for say f(x)= 2x You can put any value into the function for x however if you have say f(x)= 1/x Then should recognise that you cannot put an x value of 0 into the function as you cannot divide by 0. So the domain is the values that you can put into the function - the input values. The range is all the output values that you can get from the domain. So for f(x)= 10x where the domain is all real x values, the range is all real numbers f(x) can be made to be any value you choose.
However for f(x)= 1/x remember that x cannot equal 0, the range is all real numbers except 0. Because can you ever divide a non zero number and get 0. The answer is no.
So in summary, the domain is all the values that you can put into the function, and the range is all the values that you get coming out of the function.
If you're not sure just think domain is input values and range is output values - there is slightly more to it but I have simplified it a bit