How do you solve the following linear system: #x + y = -3, y = 2x #?

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Answer 1 · 2018-03-28T17:43:49

#x=-1#
#y=-2#

Solve by substitution:
#x+y=-3#
#y=2x#

Since you were already given that #y=2x# plug it into the first equation to solve for x:

#x+ (2x) = -3# (Combine like terms)
#3x=-3# (Divide by 3 to isolate variable)
#x=-1#

Now that you have solved for x, plug it into either equation to solve for y:

#y=2(-1)#
#y=-2#

Check the answer by plugging in both variables into equation 1:

#-1+ (-2)=-3#
#-3=-3#