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Question 398222: Trying to check my daughter's homework, not sure I remember how.
Q. Solve by graphing: y=-x+2 & 3x+3y=12
A. She has 12 = -3x+3y & (0,2) as answers and a graph that doesn't look right to me.
If you can walk me through this prob., I can prob. help her on the others.
Thanks in advance for your help!
Found 2 solutions by stanbon, Edwin McCravy:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Q. Solve by graphing: y=-x+2 & 3x+3y=12
A. She has 12 = -3x+3y & (0,2) as answers and a graph that doesn't look right to me.
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You can check that answer by letting x = 0 and y = 2
in the two sentences.
You would get:
2 = 0+2 which is ok
You would also get:
3*0+3*2 = 12
0+6 = 12
6 = 12 which is not ok
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Graph each equation by plotting 2 points and drawing a line thru them.
y = -x+2
Let x = 0, then y = 2 giving you point (0,2)
Let x = 1, then y = -1+2 = 1 giving you point (1,1)
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3x+3y=12
Let x = 0, then 3y= 12, and y = 4 giving you point (0,4)
Let x = 2, then 3*2+3y=12 and 3y = 6 so y = 2 giving you point (2,2)
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Do you see there is no solution because the lines are parallel.
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Cheers,
Stan H.
Answer by Edwin McCravy(20064)  (Show Source):
You can put this solution on YOUR website!
y=-x+2
get some points for the line y = -x+2
x | y
0 |
-1 |
4 |
x=0 x=-1 x=4
y = -x+2 y = -x+2 y = -x+2
y = -0+2 y = = -(-1)+2 y = -(4)+2
y = 2 y = +1+2 y = -4+2
y = 3 y = -2
x | y
0 | 2
-1 | 3
4 |-2
Plot those points and connect them:
Now get some points for the other line 3x+3y=12
x | y
0 |
-1 |
4 |
x=0 x=-1 x=4
3x+3y=12 3x+3y=12 3x+3y=12
3(0)+3y=12 3(-1)+3y=12 3(4)+3y=12
0+3y=12 -3 + 3y=12 12+3y=12
3y=12 3y=15 3y= 0
y=4 y= 5 y= 0
x | y
0 | 4
-1 | 5
4 | 0
Plot those points and connect them:
The lines do not intersect since they are parallel, so
there is no solution.
Edwin
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