Question

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How do you determine whether to use substitution or elimination to solve a system of equations?

(written response)

Answer 1

Hi there!

Generally, any form is fine, since you always get the same solutions (if you're doing it correctly), but usually, if you encounter something like y = 3x + 2 when the value of y is already given to you, you can just plug the value of y into the other equation and use substitution, but other than that, if the question allows, you should use elimination.

Hope this helps!

Answer 2

Use substitution when either and x or y is given, for instance: x = 2y + 3 or y = 8x - 9.

Use elimination when a number from both equations can cancel each other out, for example:
2x + 3y = 19
-2x + 7y = 12

Hope this helps!