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Students learn how to set up and solve a pair of simultaneous equations using the elimination method. Learning progresses from solving equations where the coefficients are equal to setting up a pair of equations with different coefficients from known facts.

This unit takes place in Term 2 of Year 11 and follows on from solving equations with a single unknown.

**Prerequisite Knowledge**

- Solve two simultaneous equations in two variables algebraically;
- Find approximate solutions to simultaneous equations in two variables using a graph
- Translate simple situations or procedures into algebraic expressions or formulae; derive an equation

**Success Criteria**

- Solve two simultaneous equations in two variables algebraically;
- Find approximate solutions using a graph

**Key Concepts**

- For every unknown an equation is needed.
- Students need to have a secure understanding of adding and subtracting with negatives when eliminating an unknown.
- Coefficients need to be equal in magnitude to eliminate an unknown.
- Students need to check their solutions by substituting the calculated values into the original equations.

**Common Misconceptions**

- Students often struggle knowing when to add or subtract the equations to eliminate the unknown. Review addition with negatives to address this.
- Equations need to be aligned so that unknowns can be easily added or subtracted. If equations are not aligned students may add or subtract with non like variables.
- Students often try to eliminate variables with their coefficients being equal

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