For example:

1) a general rule is you can not divide by 0, so you need to find if anything x equals has the bottom equal 0.

4 – X^2 = 0 – so 4 minus what equals 0 – well 4 -4 = 0. so you can not end up with 4 – 4 on the bottom.

so is there anything that makes X^2 = 4?

You look at it & know 2^2=4 and -2^2=4, so X can not equal 2 or -2.

so X is all real numbers except 2 & -2

2) I would try graphing on a cacluator & seeing if there are any spots you get no X value

3) same as 1 – you can not get the square root of a negative number, so figure out when 8-2X=0

hope this helps & good luck with your homework!