We recall that to subtract one number from another, we change the sign of the subtrahend and proceed as in addition. It is sometimes easier to see the result of changing signs in the subtrahend if the minus sign preceding the parentheses is regarded as a multiplier. Minus times plus is minus, so the third term is -2. This same result can be reached just as easily, in an arithmetic expression, by combining the numbers within the parentheses before applying the negative sign which precedes the parentheses. However, in an algebraic expression with no like terms such combination is not possible.
Many expressions contain more than one set of parentheses, brackets, and other symbols of grouping.
In removing symbols of grouping, it is possible to proceed from the outside inward or from the inside outward. For the beginner, it is simpler to start on the inside and work toward the outside, collecting terms and simplifying as one proceeds. When it is desired to enclose a group of terms in parentheses, the group of terms remains unchanged if the sign preceding the parentheses is positive. In problems 1 .through 4, remove the symbols of grouping and combine like terms. Integrated Publishing's Official Web Page Click here for a current index of everything on this web site.