Question 23690: Please help me solve the following equations
X+3y=4
2x-y=8
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! Look at my Lessons on Simultaneous equation, on this website... they help.
solution is:
x+3y=4 --eqn1
2x-y=8 --eqn2
scale up eqn1 by factor 2, giving:
2x+6y=8 --eqn1
2x-y=8 --eqn2
Now, the x-terms are the same digit...both a 2. Looking at the signs of these, they are the SSSSSSSSSame (both +), so we SSSSSSSSubtract the equations, to give:
5y = 0
so y = 0.
Hence, x+3y=4 becomes
x+3(0) = 4
x = 4
and CHECK in the other equation:
2x-y=8 becomes
2(4)-0 = 8
8=8 --> which is correct
jon.
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