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Question 964868: trying to solve by graphing but can find solution. help me please.
2x-y=-8
-3x+2y=10
Found 3 solutions by Alan3354, t0hierry, Edwin McCravy:
Answer by Alan3354(69443)   (Show Source):
Answer by t0hierry(194)  (Show Source):
Answer by Edwin McCravy(20059)  (Show Source):
You can put this solution on YOUR website!
The other tutors were no help. You are supposed to do it by graphing,
not by elimination, as the first one suggests. The second tutor tried
to do it that way, but his answer is wrong. Here's how to do it by
graphing.
Find three points on the first line:
x|y
0|
|2
-8|
2x-y = -8 2x-y = -8 2x-y = -8
2(0)-y = -8 2x-2 = -8 2(-8)-y = -8
0-y = -8 2x = -6 -16-y = -8
-y = -8 x = -3 -y = 8
y = 8 y = -8
x|y
0|8
-3|2
-8|-8
Plot them and draw a line through them.
You have to be accurate, so use graph paper and a ruler or straight edge.
---------------------------------------
Find three points on the second line:
x|y
0|
|2
-8|
-3x+2y = 10 -3x+2y = 10 -3x+2y = 10
-3(0)+2y = 10 -3x+2(2) = 10 -3(-8)+2y = 10
2y = 10 -3x+4 = 10 24+2y = 10
y = 5 -3x = 6 2y = -14
x = -2 y = -7
x|y
0|5
-2|2
-8|-7
Plot them and draw a line through them:
Notice the point where the two lines cross (intersect). I'll make it red.
From that point where the two lines intersect, draw one vertical line directly
to the x-axis and draw another horizontal line directly to the y-axis. I'll
draw those in green:
So the value of x is x=-6, since one green line touches the x-axis at -6
and the value of y is y=-4, since the other green line touches the y-axis at -4.
So the answer is (x,y) = (-6,-4)
Check by substituting:
2x-y = -8 -3x+2y = 10
2(-6)-(-4) = -8 -3(-6)+2(-4) = 10
-12+4 = -8 18-8 = 10
-8 = -8 10 = 10
The solution (x,y) = (-6,-4) is correct.
Edwin
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