Year 9 Maths — Linear equations in two variables

Find solutions of an equation like 2x + y = 7 and read its graph as a straight line.

Name: ________________________

1.The graph of every linear equation in two variables is...
- a) a curve
- b) a straight line
- c) a single point
- d) a circle
2.Written in the form ax + by + c = 0, the equation 3x = 5 has a = 3 and c = -5. What is b?
3.In the equation 2x + y = 7, what is y when x = 3?
4.Each pair of coordinates solves exactly one of these equations. Match them up.
- (1, 4)
- (2, 6)
- (0, 7)
- (3, 3)
- x = y
- x + y = 5
- y = 3x
- y = 7
5.Is (2, 3) a solution of x + y = 5?
- a) No — it solves x - y = 5 instead
- b) Yes — 2 + 3 comes to 5
- c) Only if x and y are swapped over
- d) No — no pair of numbers can solve it
6.How many solutions does a linear equation in two variables have?
- a) Exactly one
- b) Infinitely many
- c) Exactly two
- d) None
7.Two numbers add up to 12. Calling them x and y, the equation is x + y = c. What is c?
8.The line 2x + y = 6 crosses the y-axis. Give the y-coordinate of that crossing point.

Answer key — Year 9 Maths — Linear equations in two variables