ACT Preparation / Unit 9 ACT 0827 short lesson, about 20 seconds
Elimination
Captions available
The idea
Elimination adds or subtracts the equations so one variable cancels, after multiplying one or both by constants so its coefficients are opposites.
In practice
x + 2y = 7 and 3x − 2y = 5 add to 4x = 12, so x = 3 and y = 2.
Where people slip
Multiply every term of an equation, including the constant, when scaling it.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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