★ Topic Review — Linear Equations and Their Graphs
This review covers all four lessons: Solving Linear Equations and Inequalities, Graphing Linear Functions, Linear Models and Applications, and Simultaneous Equations. Questions increase in difficulty.
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Fluency — Solving linear equations and inequalities
- (a) Solve: 5x − 8 = 2x + 7
- (b) Solve: (3x + 1)/4 = (x − 2)/2
- (c) Solve the inequality and represent on a number line: 3 − 2x > 11
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Fluency — Features of a linear function
For the line y = −4x + 8:
- (a) State the gradient m and y-intercept c.
- (b) Find the x-intercept.
- (c) Find the y-value when x = −3.
- (d) Find the x-value when y = −4.
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Fluency — Simultaneous equations
- (a) Solve by substitution: 2x + 3y = 15 and x − y = 0
- (b) Solve by elimination: 3x + 2y = 16 and 3x − y = 7
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Understanding — Equation of a line
Find the equation of the line through (−2, 5) with gradient −3.
- (a) Write in gradient–intercept form y = mx + c.
- (b) Write in general form ax + by + c = 0 (with integer coefficients).
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Understanding — Parallel, perpendicular, or same line?
Are the lines y = 3x − 1 and 2y = 6x + 4 parallel, perpendicular, or the same line? Explain fully.
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Understanding — Perpendicular line
Find the equation of the line perpendicular to y = 4x − 3 that passes through (8, 1).
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Understanding — Linear model: mobile data
A mobile plan includes 10 GB of data. Each additional GB costs $5.
- (a) Write a cost model C for extra data, in terms of e (GB used over the 10 GB limit).
- (b) Find the extra cost if the total data used in a month is 13.6 GB.
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Understanding — Multi-step equation
Solve: 4(x − 2) − 3(2x + 1) = −5
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Understanding — Simultaneous equations: ticket sales
Adult tickets cost $22 each and child tickets cost $14 each. A group of 12 people paid a total of $204. How many adults and how many children were in the group?
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Understanding — Spring model
A spring is 10 cm at rest and stretches 2 cm for every 1 N of force applied.
- (a) Write the equation for length L (cm) in terms of force F (N).
- (b) Find the length at F = 6 N.
- (c) What force would cause a length of 22 cm?
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Understanding — Parallel line from general form
Find the equation of the line through (2, −3) that is parallel to 4x − 2y = 10.
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Problem Solving — Inequality with algebraic fractions
Solve the inequality (x + 3)/2 ≥ (2x − 1)/3 and represent the solution on a number line.
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Problem Solving — Comparing car hire companies
Luxury Cars: $120/day + $0.35/km. Budget Wheels: $75/day + $0.52/km.
- (a) Write cost equations for each company for one day in terms of km travelled (k).
- (b) Find the km per day that makes both companies equal cost.
- (c) Which company is cheaper for a 3-day trip with 150 km/day? How much is saved?
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Problem Solving — Finding k
A straight line passes through (1, k) and (k, 9) and has gradient 2.
- (a) Use the gradient formula to write an equation in k and solve for k.
- (b) Write the coordinates of both points and find the equation of the line.
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Problem Solving — Resource allocation
A factory produces widgets (x) and gadgets (y).
Each widget uses 4 kg metal + 2 hr labour.
Each gadget uses 3 kg metal + 5 hr labour.
Available per day: 48 kg metal, 45 hr labour.Solve the simultaneous equations to find how many widgets and gadgets should be produced per day to use all available metal and labour.