f.2 simultaneous equation~~~

1.3x+2y=x-6=0
3x + 2y = 0...(1)
x - 6 = 0...(2)
By (2) : x = 6 , sub to (1):
3(6) + 2y = 0
2y = - 18
y = - 9
2.7x+2y-7=3x-y=15
7x + 2y - 7 = 15...(1)
3x - y = 15...(2)
By (2): y = 3x - 15 , sub it to (1):
7x + 2(3x - 15) - 7 = 15
7x + 6x - 37 = 15
13x = 52
x = 4
y = 3(4) - 15 = - 3
3.5x-3y-11=4x-7y-18=0
5x - 3y - 11 = 0...(1)
4x - 7y - 18 = 0...(2)
By (1) :
y = (5x - 11) / 3 , sub it to (2) :
4x - 7(5x - 11)/3 - 18 = 0
12x - 7(5x - 11) = 54
12x - 35x + 77 = 54
23x = 23
x = 1
y = (5*1 - 11)/3 = - 2

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