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Systems of Linear Equations: Elimination by Substitution
cnx.orgThis site goes over when it's best to use substitution versus addition/elimination. Of course, you can always use either way, but one way will sometimes be a lot more efficient. As you read through this text, you'll see some practice problems that engage you. Towards the end of this text, we will cover concepts that haven't been discussed in detail elsewhere on this board: the two equations may be lines that are parallel; therefore, they have the same slope, never intersect, and don't have a common solution. The two equations may also equal each other (though it may be hard to detect this). In that case, the lines are the *exact same* line on a Cartesian plane, and don't have a common intersecting point as well.More ...Less ...