Question

DO THIS
1. Solve the following systems of equations :
i) x - 2y = 0
ii) x + y = 2
3x + 4y = 20
2x + 2y = 4
iii) 2x - y = 4
4x - 2y = 6​

Answer 1

i) x = 2y
x = 2 - y
Therefore,
2y = 2 - y
2y + y = 2
y = 2/3
Since x = 2y,
x = 2(2/3)
x = 4/3

ii) 3x + 4y = 20 (1)
2x + 2y = 4 (2)
2x = 4 - 2y
x = 2 - y (3)
Substituting (3) in (1),
3(2 - y) + 4y = 20
6 - 3y + 4y = 20
y = 14 (4)
Substituting (4) in (3),
x = 2 - 14
x = -12

iii) 2x - y = 4 (1)
y = 2x - 4 (3)
4x - 2y = 6 (2)
Substituting (3) in (2),
4x - 2(2x - 4) = 6
4x - 4x + 8 = 6
UNDEFINED.
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This question (iii) is wrong. Please check.