### Math 9 * Rational Numbers

```
What is a rational number?
› A number that can be written as a fraction
(form A/B).
Ex.
a) 7

b) 0.168
c) √9
Irrational number?
› A number that can not be written as a
fraction (form m/n, where n≠0).
Ex.
a) √2
b) ∏
c) 9
Ex1.
-6 – 3
-
+
0
Ex2.
(-2) + 5
-
+
0
Ex3.
(+7) + (-4)
=
=
7 - 4
3
-
+
0

3 + (-7)  3 - 7
› “The negative wins out”

5 - (-3)  5 + 3
*Skills assessment Wednesday
a) -6 + 8
=2
d) (-2) + (-4)
= -2 – 4
= -6
b) 3 + (-4)
=3–4
= -1
e) (+9) – (-8)
=9+8
= 17
c) (-1) + (-1)
= -1 – 1
= -2
f) (-5) – (-5)
= -5 + 5
= 0

Complete Lesson #1
a) (-3) + (-7)

b) (+6) – (-9)
c) (-6) – (-5)+ (-7)
The top of Currie Mountain is 156m above
the St. John River. Mr. Glenwright’s house in
Devon is 14m below the St. John River. What
is the difference in altitude between the
top of Currie Mountain and Mr. Glenwright’s
house.

The top of Currie Mountain is 156m above
the St. John River. Mr. Glenwright’s house in
Devon is 14m below the St. John River. What
is the difference in altitude between the
top of Currie Mountain and Mr. Glenwright’s
house.
Ex. Does the order of the integers affect the
a) (+14)- (-12) and (-12) – (+14)
b) (-11)+(-9) and (-9)+(-11)
Ex2. Evaluate when x = -2, y = +4, and z = -7
a)
x–y–z
b) x + y + z
c) y – z - x

A positive multiplied by a positive equals
a positive. Ex. 3 x 4 = 12

A positive multiplied by a negative
equals a negative. Ex. 4 x (-3) = -12
› “The negative wins out”.

A negative multiplied by a negative
equals a positive. Ex. (-4) x (-3) = 12
› “Two negatives make a positive”.
A new notation:
4x3 can be written as (4)(3)

4x-3 can be written as (4)(-3)

Imagine a “x” symbol in between the
brackets.
a) -6 x 8
= -48
d) (-2) + (-4)
= -2 – 4
= -6
b) 3 (-4)
=3–4
= -1
e) (+9) – (-8)
=9+8
= 17
c) (-1) + (-1)
= -1 – 1
= -2
f) (-5) – (-5)
= -5 + 5
= 0
```