Odpowiedzi

2009-12-06T00:48:01+01:00
1)
y= x+3
2x + y= 9

y= x+3
2x + x +3 = 9

y= x+3
3x = 9-3

y= x+3
x = 6/3

x = 2
y = 5

2)
y= -2x -1
x= y+7

y = -2(y+7) -1
x= y+7

y = -2y-14 -1
x= y+7

y = -2y-15
x= y+7

y+2y = -15
x= y+7

3y=-15
x=y+7

y=-15/3 = -5
x=-5+7 = 2