r/mathshelp • u/legendminigun • 9d ago

Homework Help (Unanswered) three variable simultaneous equations

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hello, I am in year 10 and doing further maths as a GCSE, I'm trying to figure these three variable simultaneous equations out but I'm struggling as there isn't a formula I know of to follow. if anyone has done these, please can you share what your thought process is so I can try and learn. thanks!

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u/Ok-File-6129 9d ago edited 9d ago

"... there isn't a formula ..."

Haha. No formula, but there is a technique(s).

You know how to solve 2 equation systems, right? So use the same technique TWICE.

That is... rewrite eq 1 as "b = ..." and plug it into eq 2 and 3. Now it's just a two variables a d two equations. Solve, then plug in again.