Christian Lawson-Perfect- Numbas at mathcentre.ac.uk

Lead developer of Numbas.

I'm happy to answer any questions - email me.

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Christian Lawson-Perfect on Solving linear simultaneous equations by elimination 8 years, 8 months ago

Gave some feedback: Has some problems

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Christian Lawson-Perfect on Solving linear simultaneous equations by elimination 8 years, 8 months ago

Saved a checkpoint:

I'd prefer it if you made sure that the solutions are always integers. Rounding errors are a distraction here. Generate the solutions first, then come up with a pair of independent equations.

I'm not sure about the way you've set out subtracting one equation from another - it's not obvious that the minus signs cancel out when there's a negative coefficient. This is one of the big problems that trips people up when doing this.

Be careful with, for example, "We have to multiply the entire first equation by 3, not just the x term to ensure we do not change the value of the equation." - an equation doesn't have a 'value'. You could instead say that you want to keep the same solution.

Right at the end of the advice, I don't like $8(5)$ for multiplication - $8 \times 5$ is much more conventional.

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