Computation with Real Numbers 25
Don’t make the error of referring to
negative numbers as “minus numbers.”The minus symbol always has a number
to its immediate left.There is never a number to the immedi-
ate left of a negative sign.Before going on, it is important that you distinguish the various uses of the
short horizontal − symbol. Thus far, this symbol has three uses: (1) as part of
a number to show that the number is negative, (2) as an indicator to fi nd the
opposite of the number that follows, and (3) as the minus symbol indicating
subtraction.Problem Given the statement −↑↑ −=↑ +−↑
(1)()−↑
()) ()( ()60 35 60
a. Describe the use of the − symbols at (1), (2), (3), and (4).
b. Express the statement −()− −=+ 60 35 − 60 in words.Solution
a. Describe the use of the − symbols at (1), (2), (3), and (4).
Step 1. Interpret each − symbol.The − symbol at (1) is an indicator to
fi nd the opposite of 35.
The − symbol at (2) is part of the num-
ber − 35 that shows − 35 is negative.
The − symbol at (3) is the minus sym-
bol indicating subtraction.
The − symbol at (4) is part of the num-
ber − 60 that shows − 60 is negative.b. Express the statement −()− −=+^6035 −^60
in words.
Step 1. Translate the statement into words.
−()− −= 60 35 +− 60 is read “the opposite of negative thirty-fi ve
minus sixty is thirty-fi ve plus negative sixty.”