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Years 7-9 Mathematics

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Number and Financial Mathematics

In Years 7-8, we work with integers, fractions, decimals, and percentages. We solve problems involving percentages and money, including calculating percentage discounts and profits.

Working with Integers

Integers include all positive and negative whole numbers, including zero. We learn to perform operations with integers and understand their real-world applications.

Practice Questions

Calculate 15% of $240.

0.15 × 240 = $36

A shirt originally costs $60 and is on sale for 25% off. What is the sale price?

Discount = 0.25 × 60 = $15, Sale price = $60 - $15 = $45

Calculate: -15 + 23 - (-7)

-15 + 23 = 8, 8 - (-7) = 8 + 7 = 15

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Algebraic Techniques

Working with Variables

We extend and apply the distributive law to the expansion of algebraic expressions. We factorise algebraic expressions by identifying numerical factors.

Expand: 3(2x + 5)

Practice Simplifying Expressions

2x + 3x - x

Practice Questions

Expand 4(3x - 2)

12x - 8

Factorise 15x + 10

5(3x + 2)

Solve for x: 3x + 7 = 22

3x = 15, x = 5

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Linear Relationships

Graphing and Equations

We plot linear relationships on the Cartesian plane with and without the use of digital technologies. We solve linear equations using algebraic techniques.

Practice Questions

Plot the points (1, 2), (2, 4), and (3, 6) on a Cartesian plane. What do you notice?

These points form a straight line with the equation y = 2x

Find the gradient of the line that passes through points (1, 3) and (4, 9)

Gradient = (9-3)/(4-1) = 6/3 = 2

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Measurement and Geometry

Geometric Reasoning

We identify corresponding, alternate, and co-interior angles when two straight lines are crossed by a transversal. We investigate conditions for two lines to be parallel.

Square
Triangle
Circle
Rectangle

Practice Questions

Calculate the area of a circle with radius 5cm.

Area = πr² = 3.14 × 25 = 78.5 cm²

Find the volume of a rectangular prism with dimensions 5cm × 6cm × 10cm.

Volume = 5 × 6 × 10 = 300 cm³

In a pair of parallel lines cut by a transversal, if one angle is 75°, what is its corresponding angle?

Corresponding angles are equal, so it would also be 75°

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Statistics and Probability

We identify and investigate data issues through numerical summaries and visual displays. We describe probabilities using fractions, decimals, and percentages, and conduct chance experiments.

Probability Experiment

Click the button to simulate rolling a die:

Practice Questions

In a class of 28 students, 16 are girls. What fraction of the class are boys?

12/28 = 3/7

If the probability of rain tomorrow is 0.3, what is the probability it won't rain?

1 - 0.3 = 0.7 or 70%

Introduction to Quadratic Equations

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What are Quadratic Equations?

Quadratic equations are polynomial equations of the form:

ax² + bx + c = 0

Where a, b, and c are constants, and a ≠ 0. The graph of a quadratic equation is always a parabola.

Key Components

  • a - Determines the parabola's direction and width
  • b - Affects the position of the vertex
  • c - The y-intercept of the parabola
Direction
Upward
Vertex
(0, 0)
Y-Intercept
(0, 0)
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The Quadratic Formula

The quadratic formula is used to find the roots (solutions) of any quadratic equation:

x = [-b ± √(b² - 4ac)] / 2a

Discriminant

The expression under the square root (b² - 4ac) is called the discriminant. It tells us about the nature of the roots:

Practice Using the Formula

Solve: x² + 5x + 6 = 0

x = [-5 ± √(25 - 24)] / 2 = [-5 ± 1]/2 → x = -2 or x = -3

Solve: 2x² - 4x - 6 = 0

x = [4 ± √(16 + 48)] / 4 = [4 ± √64]/4 = [4 ± 8]/4 → x = 3 or x = -1

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Factoring Quadratic Equations

Many quadratic equations can be solved by factoring. The general approach is to find two numbers that multiply to ac and add to b.

Factoring Patterns

Practice Factoring

Factor: x² + 7x + 12

(x + 3)(x + 4)

Factor: x² - 9

(x + 3)(x - 3)