SOLUTION: Solve using the substitution method x + y = -4; y = 3x + 2

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Question 416973: Solve using the substitution method
x + y = -4; y = 3x + 2
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

x+%2B+y+=+-4 .........1
y+=+3x+%2B+2...........2
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x+%2B+y+=+-4 .........1 ...solve for x
x+=+-y+-4 ...plug in 2
y+=+3%28-y+-4%29+%2B+2
y+=+-3y+-12+%2B+2
y+%2B3y=+-10+
4y=+-10+
y=+-10%2F4+
y=+-2.5+

x+=+-y+-4 ...plug in y
x+=+-%28-2.5%29+-4
x+=+2.5+-4
x+=+-1.5

check:

x+%2B+y+=+-4 .........1

+-1.5+%2B+%28-2.5%29+=+-4
+-1.5+-2.5+=+-4
+-4+=+-4