SOLUTION: hi, two linear equations: x=-3y x+y=4 Which points represent the common solution for the two equations? the answer is (6, -2) how did they get that? thanks

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Question 75089: hi,
two linear equations:
x=-3y
x+y=4
Which points represent the common solution for the two equations?
the answer is (6, -2) how did they get that?
thanks

Answer by checkley75(3666)   (Show Source): You can put this solution on YOUR website!
TWO WAYS TO SOLVE THIS ALGEBRACIALLY:
X=-3Y NOW REPLACE X WITH (-3Y) IN THE OTHER EQUATION AND SOLVE FOR Y
(-3Y)+Y=4
-2Y=4
T=4/-2
Y=-2 ANSWER.
NOW SUBSTITUTE -2 FOR Y & SOLVE FOR X
X=-3(-2)
X=6 ANSWER.
--------------------------------------------------------
ANOTHER SOLUTION IS TO GRAPH THE TWO EQUATIONS. THUS:
X=-3Y
-3Y=X, Y=-X/3
X+Y=4, Y=-X+4
(graph 300x200pixels, x from -6 to 10, y from -6 to 5, of TWO functions y = -x/3 and y = -x +4).

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