Algebra 1 Notes
Chapter 2 Section 2
Subtracting Rational Numbers
2 ­ 6 = ­10 ­9
­8 ­7
­6
­5 ­4
­3
­2
­1
0
1
2
3
4
5
6
7
8
9
10
­1 ­ 4 = ­10 ­9
­8 ­7
­6
­5 ­4
­3
­2
­1
0
1
2
3
4
5
6
7
8
9
10
Subtracting Numbers:
To subtract a number, add its opposite
‐4 ‐ (‐9) =
8‐ (‐4) =
‐6 ‐ 2=
(‐8/9) ‐ (‐5/6)=
Absolute Value:
The distance on a number line of a
number from the point 0
Distance = 7 units
Distance = 7 units
­10 ­9
­8 ­7
­6
­5 ­4
­3
­2
­1
0
1
2
3
4
5
6
7
8
9
Remember!! You cannot have negative
distance. Which means, the ABSOLUTE
VALUE of a number is always
___________!!!
10
Evaluate the expression ‐a ‐ b for a = ‐3 and b = ‐5
Evaluate the expression r ‐ t for t = ‐2 and r = ‐7
Evaluate the expression ‐r ‐ (‐t) for t = ‐2 and r = ‐7
Homework #2
p. 60 #5-12, 17, 18, 22, 26, 49,
52, 54
p. 66 #9-27 multiples of 3,
29, 31, 34, 35,
DUE MONDAY!!!!!
1. A rock climber climbs a mountain. The base of the
mountain is 132 ft below sea level.
a) First write an expression to represent the climber's
height below or above sea level.
b) Then find the climber's height above sea level when
he is 485 ft above the base of the mountain.
2. The temperature one winter morning is -14 degrees
Fahrenheit. Define a variable and write and expression to
find the temperature after it changes. Then evaluate your
expression for a decrease of 11 degrees Fahrenheit
Challenge Problem:
Archaeologists found a 1500-year old ship at the bottom of
the Black Sea. The ship was well preserved because oxygen
could not make the ship decay. The ship is at a depth of 1000
feet below the surface. This is about 350 feet below the
boundary between surface water, which as oxygen, and water
below, which does not have oxygen. How deep is the
boundary?
(Hint: Drawing a picture might help
you sort out the word problem!)