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About this video
The Grade 9 maths year term by term, as CAPS sets it out: whole numbers, integers, exponents, patterns and algebraic language in Term 1 (new in finance: commission, rentals and compound interest); expressions, equations, graphs and the geometry of straight lines in Term 2; 2D shapes, area and perimeter, data and probability in Term 3; 3D objects, surface area, volume and transformations in Term 4. Much of it revises Grade 8 — so go back and master what you got wrong.
What it covers
- Term 1: whole numbers, integers, exponents, patterns, functions and algebraic language
- New in Grade 9 finance: commission, rentals and compound interest
- Term 2: algebraic expressions, equations, graphs and the geometry of straight lines
- Term 3: 2D shapes, area and perimeter, data handling and probability
- Term 4: 3D objects, surface area and volume, transformation geometry
- Much of Grade 9 revises Grade 8 — go back and master what you got wrong
Extra worked examples
✍️ Extra example (Term 1, new in Grade 9): R5 000 is invested at 8% per year compound interest for 2 years. Find the final amount.
- 1A = 5 000(1 + 8/100)2Compound interest: each year's interest is added on, and then earns interest itself.
- 2= 5 000 × 1,082 = R5 8321 + 0,08 = 1,08.
- 3Simple interest would give R5 000 + 2 × R400 = R5 800Compound interest earns R32 more — the interest on the first year's interest.
✍️ Extra example (Term 2): for y = 2x − 6, find the y-intercept, the x-intercept and the gradient.
- 1x = 0: y = 2(0) − 6 = −6The y-intercept is where the line cuts the y-axis, where x = 0.
- 2y = 0: 0 = 2x − 6 → x = 3The x-intercept: y = 0.
- 3The gradient is 2In y = mx + c, the gradient is the number in front of x: the line rises 2 for every 1 to the right.
Exercises to try
Work each one out, then click to reveal the answer.
- 1Term 1: 5 taps fill a tank in 12 minutes. How long would 6 taps take?
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Indirect proportion: 5 × 12 = 60, then 60 ÷ 6 = 10 minutes - 2Term 1: an estate agent earns 6% commission on a house sold for R850 000. Find the commission.
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6/100 × 850 000 = R51 000 - 3Term 1: write 0,00045 in scientific notation.
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4,5 × 10−4 - 4Term 3: the sides of a 5 cm square are doubled. What happens to the perimeter and the area?
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perimeter: 20 cm → 40 cm (doubled); area: 25 cm² → 100 cm² (four times as big) - 5Term 4: reflect the point A(3; −2) in the x-axis, and the same point in the y-axis.
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In the x-axis: (3; 2) — the y-coordinate changes sign. In the y-axis: (−3; −2) — the x-coordinate changes sign.
