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2009-12-01T15:48:49+01:00
A)
2x - 3y = 7 | * -3
3x - 5y = 11 | * 2
-6x + 9y = -21
6x -10y = 22
------------------
-y=1
y=(-1)

2x- 3* (-1)= 7
2x=7-3
2x=4
x=2

b)
5p - 2r = 21 |*5
3p + 5r = -6 |*2
25p - 10r=105
6p+10r= -12
-----------------------
31p= 93
p= 3

5*3 - 2r =21
-2r=6
r=-3

c)
2x-3y=10 |*5
5x+5y=0 |* -2
10x-15y=50
-10x-10y=0
------------------
-25y=50
y= -2
2x- 3 * (-2) = 10
2x=4
x=2

d)
5v₁ + 4v₂ = 4 |* -5
7v₁+ 5v₂ = 6 |* 4
-25v₁ - 20v₂=-20
21v₁ + 20v₂ = 24
-----------------------
-4v₁=4
v₁=-1

5* (-1) +4v₂=4
4v₂= 9
v₂= 2¼



30 2 30
2009-12-01T16:02:17+01:00
A.
2x - 3y = 7 /*(-3)
3x - 5y = 11 /*2
-6x+9y=14
6x-5y=22
-------------------
-6x+6x+9y-5y=14+22
4y=36 /:4
y=9
2x-3y=7
y=9
2x-27=7
y=9
2x=34
y=9
x=17


B.
5p - 2r = 21 /*(-3)
3p + 5r = -6 /*5
-15p+6r=-63
15p+25r=-30
-------------------
-15p+15p+31r=-93
31r=-93
r=-3
3p+5r=-6
r=-3
3p=-6+15
r=-3
p=-3

C.
2x-3y=10 /*5
5x+5y=0 /*(-2)
10x-15y=50
-10x-10y=0
----------------
10x-10x-10y-15y=50
-25y=50
y=-2
2x-3y=10
y=-2
2x+6=10
y=-2
2x=4
y=-2
x=2

D.wychodzą mi dziwne ułamki xD
40 3 40