Question

How do you find the domain of an equation????

Answer 1

You mean a function, not a equation

Answer 2

it depends on the function, but in general you are looking for things that x CANT be, and then you remove them from the real numbers

Answer 3

Yeah a function.... How do you do it?!

Answer 4

there are three main problems, sqrt of negative numbers, log of non positive numbers, and dividing by 0.

Answer 5

So should I set it to 0?

Answer 6

Can you show the problem?

Answer 7

There are a couple, but the first on is 4x-3

Answer 8

And then it just gets more difficult as it goes on. Is there like a set rule I could use?

Answer 9

there is no change for you to divide by 0, there are no square roots, and there are no logs, so its all real numbers

Answer 10

Yes all real numbers.

Answer 11

there is not, but there are three basic ways.

example:

1) \(\frac{x^2+2}{(x-3)(x+4)}\) so we cant divide by 0 so we rule out x=3 and x=-4

2) \(\ln(x-3)\) logs must have inputs greater than 0, so x-3>0 implies x>3 so we rule out x<=3

3) \(\sqrt{4+x}\) the input must be greater than or equal to 0 so x=4>=0 implies \(x\ge-4\) so we rule out x<4.

sometimes they will make it so we need to look at two things at once

4) \(\frac{x^2+1}{\sqrt{x-4}}\) the denominator cant be 0, so we do x-4>0 implies x>4

so we rule out x<=4

Answer 12

on 3) that should say 4+x>=0 implies...

Answer 13

Oooooooooh okay. That makes since. Thank you!