2.2 Linear Equations

• Linear equations in two unknowns
• Solving linear equations by the elimination method

• form linear equations in two unknowns in real-life situations
• solve linear equations in two unknowns by substitution method in real-life situations
• solve linear equations in two unknowns by elimination method in real-life situations
• apply linear equations in two unknowns in real-life situations
• recognise use of linear equations in real life

“How do we solve linear equations in two unknowns?”

“Where do we use linear equations in two unknowns in real-life situations?”

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1. Equations in two unknowns
   40 min · 1 practice tasks · quiz
   Why one equation with two letters has endlessly many answers, and what a pair of simultaneous equations does about it.
2. Forming equations from a situation
   40 min · 1 practice tasks · quiz
   Turning a described situation into two equations by naming the unknowns and translating each fact.
3. Solving by substitution
   40 min · 1 practice tasks · quiz
   Putting what one letter equals into the other equation, so that only one unknown is left.
4. Substitution after rearranging
   40 min · 1 practice tasks · quiz
   What to do when no letter is alone: rearrange one equation first, choosing the letter that keeps the numbers whole.
5. Solving by elimination
   40 min · 1 practice tasks · quiz
   Adding or subtracting the two equations so that one letter disappears, and knowing which of the two to do.
6. Elimination after multiplying
   40 min · 1 practice tasks · quiz
   Making the terms match by multiplying whole equations, then eliminating as usual.
7. Linear equations in real life
   40 min · 1 practice tasks · quiz
   Solving real problems end to end: forming the equations, choosing a method, solving, and answering in words.