The absolute value of a positive number is itself. The absolute value of a negative number is its opposite, the opposite of the whole thing, so you need to replace the absolute value in that case with a set of parentheses with a minus sign on the outside of it. Then when you simplify the expression to get rid of the parentheses you have to distribute the minus sign into each term. Interval Notation Think of interval notation as cutting pieces out of the real line and the two numbers are the endpoints. Round brackets mean that the endpoints are not included.
Square brackets mean that they are included.
We can also use interval notation for unbounded intervals by using infinity and minus infinity, but there is always a round bracket at infinity or minus infinity, because they are not real numbers. When you use such a notation like for example the interval from 3 to infinity, it means the numbers from 3 all the way up to, but not including, infinity, which is simply all of the real numbers greater than 3. For the meaning of fractional exponents remember that the numerator is the power and the denominator is the root. For simplifying with powers remember that the same properties that you learned about whole number exponents work for work for all rational exponents. You just have to remember how to do fraction operations.