Question

find the domain of the function: f(x)= 2x by working it out

Answer 1

what do you mean "by woring it out"?

Answer 2

working ....

Answer 3

we have to show our work and im not sure how to even do that

Answer 4

The domain is what it is simply because there is no numbers that make this function go bad; 2 times any number is good

Answer 5

show your work by drawing a graph perhaps?

Answer 6

how?

Answer 7

there is no spot that is NOT in the domain; so it has to be from -inf to inf

Answer 8

i still don't understand

Answer 9

how do you show infinity? you cant, there has to be some point where you let reason pervade

Answer 10

define the term "domain" for me, lets see if you have an understanding at that level first

Answer 11

nevermind

Answer 12

in order to be asking this level of a question, you have to have some basic concepts under your belt first.

Answer 13

ok, but good luck out there :)

Answer 14

what about if it says f(x)=2x -1 \[\le\] x \[\le\] 5 ??

Answer 15

that would be defineing a domain; in other words, the values for x to be used are between -1 and 5 inclusivley

Answer 16

how would I go about working that out step by step?

Answer 17

ideally, you would test all the values within the domain and check to see that they produce valid results. but maybe im not reading the "working out" part right

Answer 18

formal proofs and such that you work out in higher levels of math might provide an insight, but I havent gone thru those in years

Answer 19

being that this is a polynomial expression; it is defined such that it has no "solutions" that result in an indeterminable form such as 0/0 or some such

Answer 20

its linear at that which means that if its true for spot, its true for all spots since everything is lined up right after the other