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#1 Help Me ! » Solving Systems of Equations Using Substitution Method and Elimination » 2013-10-24 09:17:03

lisathedork
Replies: 2

My progress so far, am I'm doing this right?

10.   y = (2/3)x - 1
        y = -x + 4

2/3x – 1 = -x + 4
2/3x + x = 4 + 1
5/3x = 5

5x = 15
X=3
Y=-x + 4
Y = -3 + 4
Y=1

11.   x + y = 0
       3x + y = -4

X + y – (3x + y) = 0 – (-4)
X + y – 3x – y = 0 + 4
-2x = 4
X= -2

X+ y = 0
-2 + y = 0
Y = 2

12.  4x + 3y = -15
       y = x + 2

4x +3(x +2) = -15
4x + 3x + 6 = -15
7x = -21
X = -3

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Can someone help me guide me through this?

13.   x + 2y = -4
      4y = 3x + 12

14.   y = 2x
       x + y = 3

15.  x = 3 - 3y
      x + 3y = -6

16.   y = -2x + 1
        y = x - 5

17.   y = (1/2)x - 3
       y = (3/2)x – 1

18.   x + y = 2
       4y = -4x + 8

19. Why are the substitution and elimination methods necessary when we already know how to solve systems of linear equations using the graphing method?

#3 Re: Help Me ! » Graphing Systems of Linear Equations » 2013-10-24 07:57:54

Shouldn't it be like that?

2x - 3y = -2
2(0) - 3y = -2
-3y = -2
y = 2/3
(0, 2/3)
2x - 3(0) = -2
2x = -2
x = -1
(-1, 0)


4x + y = 8
4(0) + y = 8
y = 8
(0, 8)
4x + y = 8
4x + 0 = 8
4x = 8
x = 2
(2, 0)

these are just examples.




Cause I know I have to found the y = mx + b

#4 Help Me ! » Graphing Systems of Linear Equations » 2013-10-24 04:31:59

lisathedork
Replies: 5

How do I graph these?


1. y = (2/3)x - 1
y = -x + 4



2. x + y = 0
3x + y = -4

3. 4x + 3y = -15
y = x + 2



4. x + 2y = -4
4y = 3x + 12



5. y = 2x
x + y = 3



6. x = 3 - 3y
x + 3y = -6


7. y = -2x + 1
y = x - 5

8. y = (1/2)x - 3
y = (3/2)x - 1

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