Topic Review — Non-Linear Relationships
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Identify type and key feature. Fluency
For each equation, state whether it is a parabola, hyperbola, circle, or exponential function, then identify the named feature.
- (a) y = 4/x — state the asymptotes
- (b) y = 5x — state the y-intercept
- (c) (x − 1)² + (y + 3)² = 36 — state the centre and radius
- (d) y = 2x² − 8x + 1 — state the axis of symmetry
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Hyperbola y = 15/x. Fluency
- (a) Find y when x = 3, x = −5, and x = 1/2.
- (b) Find x when y = 6, y = −3, and y = 30.
- (c) Do the branches appear in Quadrants 1 & 3 or Quadrants 2 & 4? Explain using the value of k.
- (d) State the domain and range.
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Circle (x + 2)² + (y − 1)² = 49. Fluency
- (a) State the centre and radius.
- (b) State the domain and range.
- (c) Does the point (5, 1) lie on the circle? Show your working.
- (d) Is this relation a function? Explain.
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Exponential y = 2 × 3x. Fluency
- (a) Find the y-intercept.
- (b) State the horizontal asymptote.
- (c) Find y when x = 2.
- (d) Find the smallest integer x such that y > 100.
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Write the equation. Fluency
Write the equation of the graph satisfying each description.
- (a) A hyperbola y = k/x passing through (4, −3).
- (b) A circle centred at (−1, 4) with radius 2.
- (c) An exponential y = b × ax passing through (0, 5) and (1, 10).
- (d) A circle centred at the origin passing through (−3, 4).
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Completing the square for circles. Understanding
Rewrite each equation in standard form. State the centre and radius.
- (a) x² + y² − 4x + 6y − 3 = 0
- (b) x² + y² − 10x + 4y + 20 = 0
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Town population growth. Understanding
A town has a population of 5000 and grows at 4% per year. The population after t years is P = 5000 × 1.04t.
- (a) Find the population after 1 year.
- (b) Find the population after 10 years, to the nearest whole number.
- (c) After how many complete years does the population first exceed 6000? (Use trial values.)
- (d) The population formula has the form P = A × bt. State the values of A and b, and explain what each represents in context.
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Comparing y = 20/x and y = 2x. Understanding
- (a) At x = 1, which function gives a larger value?
- (b) At x = 4, which function gives a larger value?
- (c) For very large values of x (say x = 100), which function gives a much larger value? Explain.
- (d) As x → +∞, what happens to the value of y = 20/x? What is the horizontal asymptote? Does y = 2x have the same asymptote?
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Identify from key features. Understanding
Each description refers to a different graph type (parabola, hyperbola, circle, exponential). Identify each type.
- (a) The graph passes through (0, 1), never crosses the x-axis, and curves steeply upward for x > 0.
- (b) The graph has two branches that approach, but never touch, both coordinate axes.
- (c) The graph is a closed curve, centred at a point, and fails the vertical line test.
- (d) The graph has a turning point at (3, −2), opens upward, and crosses the x-axis at two points.
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Shifted hyperbola y = k/(x − 2) + 3. Understanding
- (a) Find k if the graph passes through (4, 7).
- (b) Using your value of k, find y when x = 6.
- (c) Find x when y = 1.
- (d) State the domain and range.
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Fish population decline. Problem Solving
A lake is monitored after a pollution event. The fish population starts at 200 and decreases by 15% each year: N = 200 × (0.85)t.
- (a) Find the population after 2 years, to the nearest whole number.
- (b) Find the population after 5 years, to the nearest whole number.
- (c) After how many complete years does the population first fall below 100?
- (d) The model predicts N approaches 0 but never reaches it. What does this mean in the real-world context, and at what point does the model become unrealistic?
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Intersection of a circle and a hyperbola. Problem Solving
Consider the circle x² + y² = 10 and the hyperbola y = 3/x.
- (a) Substitute y = 3/x into x² + y² = 10 and show that the result simplifies to x4 − 10x² + 9 = 0.
- (b) Factorise x4 − 10x² + 9 as (x² − 1)(x² − 9), and hence find all four values of x.
- (c) Find the corresponding y-value for each x, and list all four intersection points.
- (d) Verify that the point (3, 1) lies on both curves.