Respostas
a) 1/3x +2y = 5 (×3)
3/3x + 6y = 15
x + 6y = 15
x - 3y = -3 (×-1)
x +6y = 15
- x +3y = 3
x +6y = 15
__________+
9y = 18
y= 18/9
y = 2
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x - 3y = - 3
x - 3.2 = -3
x - 6 = -3
x= -3+6
x= +3
b) 1/3x + 1/3y = 1 (×3)
3/3x + 3/3y = 3
x + y = 3
x - 5y = 9
x + y = 3 (×-1)
x - 5y = 9
-x - y = -3
________+
- 6y = 6
y= 6/-6
y= - 1
x - 5y = 9
x - 5.(-1)= 9
x +5 = 9
x= 9-5
x= 4
c) x + 1/2y = 1 (×2)
2x + 2/2y = 2
2x + y = 2
3x + y = 1
2x + y = 2 (× -1)
3x + y = 1
-2x -y = -2
_________+
x = -1
3x + y = 1
3.(-1) +y = 1
- 3 + y = 1
y= 1 +3
y= 4
d) 1/2x - 1/2y = -5. (× 2)
2/2x - 2/2y = - 10
x - y = - 10
x + 2y = - 4 (×-1)
x - y= -10
- x - 2y = +4
x - y = -10
__________+
- 3y = -6
y = -6/-3
y= +2
x - y = - 10
x - 2 = -10
x= - 10 +2
x= - 8