Most of math is just a set of rules.  Once you learn the rules, you can do all the computations.  That is, once you know how to add, subtract, multiply and divide. This is best illustrated in how you find the domains of functions.

For example, any question that asks you to find the domain of any function is a very simple question.  Just know the all the rules, and you can answer any question.  For this type of question, there’s mainly only 3 rules.

1.  Don’t divide by Zero
2. Can’t Square Root Negative Numbers
3. Can’t Take the Log of Negative Numbers

Once you know the rules, every find the domain problem, becomes simply finding out when one of these rules apply.  Here’s a few examples

X^2
Well, is it dividng? No.  Is there a Square Root? No.  Is there a Log?  No
Thus: The domain is all real #s.

X^2/X
Technically, this equals just X, HOWEVER, since you devide by it, there’s one rule being broken,
since you are dividing, whenever the denominator is zero, can’t exist, so thus, the domain of this
is all real #s EXCEPT zero

X^2/X-3
This problem is relatively the same, EXCEPT for the minus 3 in the denominator.
Once again, where the denominator = 0 is where this doesn’t exist
The denominator = 0 WHEN x = 3, thus
The answer is all real #s EXCEPT 3

sqrt (X+4)
Here the squareroot can’t be negative, so you find where it becomes negative
It becomes negative when X is less than 4 (Plus you CAN take sqrt of ZERO) SO
The Domain is All Real #s >= -4 OR in Interval Notation [-4, inf) (can’t reach infinity)

Logs function the same way as square roots.

There’s the rules, now go out and find some domains!

If you have any questions, feel free to contact me
I am eager to answer your math questions, or perhaps
even schedule a tutoring session.