<< Chapter < Page | Chapter >> Page > |
We know from our experience with arithmetic that the subtraction
produces 3, that is,
. Illustrating this process on the number line suggests a rule for subtracting signed numbers.
We begin at 0, the origin.
Since 5 is positive, we move 5 units to the right.
Then, we move
2 units to the left to get to 3. (This reminds us of addition with a negative number.)
This illustration suggests that
is the same as
.
This leads us directly to the definition of subtraction.
The preceding definition suggests the rule for subtracting signed numbers.
Perform the subtractions.
The high temperature today in Lake Tahoe was
. The low temperature tonight is expected to be
. How many degrees is the temperature expected to drop?
We need to find the difference between 26 and
.
Thus, the expected temperature drop is .
Perform the subtractions.
For the following exercises, perform the indicated operations.
When a particular machine is operating properly, its meter will read 34. If a broken bearing in the machine causes the meter reading to drop by 45 units, what is the meter reading?
The low temperature today in Denver was and the high was . What is the temperature difference?
( [link] ) Simplify . Assume .
( [link] ) Find the sum. .
Notification Switch
Would you like to follow the 'Elementary algebra' conversation and receive update notifications?