-7x+2y=2
x+3y=-20
how would you solve this solution
2007-02-07 02:21:45 · 6 answers · asked by danielle 2 in Science & Mathematics ➔ Mathematics
- 7x + 2y = 2- - - - - -Equation 1
x + 3y = - 20- -- - - - Equation 2
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Multiply equation 2 by 7
x + 3y = - 20
7(x) + 7(3y) = - 7(20)
7x + 21y = - 140
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- 7x + 2y = 2
7x + 21y = - 140
- - - - - - - - - - - -
23y = - 138
23y/23 = - 138/23
y = 138/23
y = - 6
The answer is y = - 6
Insert the y value into equation 2
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x + 3y = - 20
x + 3(- 6) = - 20
x + (- 18) = - 20
x - 18 = - 20
x - 18 + 18 = - 20 + 18
x = - 2
The answer is x = - 2
Insert the x value into equation 2
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Check for equation 2
x + 3y = - 20
- 2 + 3(- 6) = - 20
-2 + (- 18) = - 20
- 2 - 18 = - 20
- 20 = - 20
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Check for equation 1
- 7x + 2y = 2
- 7(- 2) + 2(- 6) = 2
-( - 14) + (- 12) = 2
14 - 12 = 2
2 = 2
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The solution set { - 2, - 6 }
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2007-02-07 02:57:31 · answer #1 · answered by SAMUEL D 7 · 2⤊ 0⤋
Multiply the second equation by 7:
-7x+2y=2
7x+21y=-140
==========
23y=-138
y=-6
-7x+2(-6)=2
-7x-12=2
-7x=14
x=-2
The solution set is (-2,-6)
Check:
-7(-2)+2(-6)=2
14-12=2
2=2
-2+3(-6)=-20
-2-18=-20
-20=-20
2007-02-07 03:16:27 · answer #2 · answered by Anonymous · 0⤊ 0⤋
-7x+2y=2
+7 +7
0+9y=2
/9 /9
y= 4.5
Next Question
x+3y=20
-3 -3
-3x=20
/-3 /-3
x= -6.67
just guessing
2007-02-07 02:27:59 · answer #3 · answered by queenofkings2525 3 · 1⤊ 0⤋
-7x +2y =2
Y=(2+7x)/2
Y=(7x)/2+1
Y=4.5x+1
2007-02-07 02:29:52 · answer #4 · answered by poseidenneptune 5 · 1⤊ 0⤋
x=-2
y=-6
2007-02-07 02:34:39 · answer #5 · answered by Anonymous · 1⤊ 0⤋
what variable are you trying to find? xor y?
2007-02-07 02:28:11 · answer #6 · answered by Jessica 2 · 1⤊ 1⤋