How do you solve the following system: #3x-y=12, 4x-y=6 #?

1 Answer
Noah G
Feb 24, 2016

I'll solve this systems of equations for you by substitution

Explanation:

We must first isolate a variable.

#3x - y = 12#

#-y = 12 - 3x#

#y = -12 + 3x#

Now, knowing y, we can substitute for y in the other equation.

#4x - (-12 + 3x) = 6#

#4x + 12 - 3x = 6#

#x = -6#

#3(-6) - y = 12#

#-18 - y = 12#

#-y = 30#

#y = -30#

The solution set is #{-6, -30}#. Note that the solution set must always be of the form #{x, y}#, as noted in graphing. Eg. the point (8,5) is 8 on the x axis and 5 on the y axis graph.

Hopefully this helps!

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