Math 9 – Rational Numbers

Chapter 3

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

Back to basicsEx1. -6 – 3

Ex2. (-2) + 5

Ex3. (+7) + (-4)

= 7 - 4 = 3

0

- +

0

- +

0

- +

Positive/Negative Rules

Adding a negative subtraction 3 + (-7) 3 - 7

› “The negative wins out”

Subtracting a negative addition 5 - (-3) 5 + 3

*Skills assessment Wednesday

You try

a) -6 + 8 b) 3 + (-4) c) (-1) + (-1)

d) (-2) + (-4) e) (+9) – (-8) f) (-5) – (-5)

= 2 = 3 – 4= -1

= -1 – 1= -2

= -2 – 4= -6

= 9 + 8= 17

= -5 + 5= 0

Class work

Complete Lesson #1

Math 9 – Sept. 10th

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.

a) (-3) + (-7) b) (+6) – (-9) c) (-6) – (-5)+ (-7)

Math 9 – Sept. 10th 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.

Math 9 – Sept. 10th Ex. Does the order of the integers affect the

answer? If so, how?a) (+14)- (-12) and (-12) – (+14)

b) (-11)+(-9) and (-9)+(-11)

Math 9 – Sept. 10th Ex2. Evaluate when x = -2, y = +4, and z = -7

a) x – y – z b) x + y + z c) y – z - x

Multiply/Divide Rules 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”.

Multiply/Divide Rules 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.

You try

a) -6 x 8 b) 3 (-4) c) (-1) + (-1)

d) (-2) + (-4) e) (+9) – (-8) f) (-5) – (-5)

= -48 = 3 – 4= -1

= -1 – 1= -2

= -2 – 4= -6

= 9 + 8= 17

= -5 + 5= 0