SOLUTION: 1) y=x y=-x 2)y=-x y=x+9 i have 12 problems just like this, and the instuctions in the book i dont get. pleezzz help than

Question 70506: 1) y=x
y=-x
2)y=-x
y=x+9
i have 12 problems just like this, and the instuctions
in the book i dont get. pleezzz help thank you
Found 3 solutions by checkley75, madmaths, pleasuretohelp:
Answer by checkley75(3666)   (Show Source): You can put this solution on YOUR website!
Y=X & Y=-X CANNOT BE TRUE!!!!!! SUBSTITUTING X FOR Y IN THE SECOND EQUATION WE GET X=-X?????????????????????
-------------------------------
Y=-X SUBSTITUTING -X FOR Y IN THE SECOND EQUATION WE GET
-X=X+9
-X-X=9
-2X=9
X=9/-2
X=-4.5
-----------------------------------------
IF THESE ARE LINE EQUATIONS THEN:
(graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = x and y = -x).
-----------------------------------------
(graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions y = -x and y = x +9).

Answer by madmaths(2)   (Show Source): You can put this solution on YOUR website!
ok,,reply for question 2)
From eq 1)
y=-x
substitute the value of y from eq1) in eq 2)
y=x+9
-x=x+9
-x-x=9
-2x=9
x=-9/2
now substitute this value of x in eq 1)
y=-(-9/2)
so y=9/2
Answer by pleasuretohelp(9)   (Show Source): You can put this solution on YOUR website!
y=x
y=-x
Let's take your problem #1 as an example.
First, you need to set both equations = 0.
y = x becomes y - x = 0
y = -x becomes y + x = 0
Second, perform subtraction between those equations.
y - x = 0
y + x = 0
__________ -
0 - 2x = 0
Third, simplify.
0 - 2x = 0
-2x = 0
Fourth, divide both sides by -2.
-2x/-2 = 0/-2
x = 0
Fifth, since we know that x = 0, recall that the original problem was:
y=x
y=-x
Therefore, we can take either y=x or y=-x to substitute x as a 0.
Either way, y = 0.
So, the answer is x = 0 and y = 0.
Why don't you try question #2 your own? If you have problems, post back the question and I'll be glad to help you :)
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