Odpowiedzi

2009-11-25T19:09:37+01:00
A
5x+4y=4 /*-5
7x+5y=6 /*4

-25x-20y=-20
28x+20y=24
---------------
3x=4 /:3
x= 4/3
x=1i1/3

5x+4y=4 /*-7
7x+5y=6 /*5

-35x-28y=-28
35x+25y=30
------------------
-3y=2 /:-3
y=-2/3
2009-11-25T19:18:41+01:00
A)
5x+4y=4 /*(-5)
7x+5y=6 /*6

-25x-20y=-20
28x+20y=24
------------------ dodajemy
3x=4
x=4/3

5*4/3+4y=4
4y=4-20/3
4y=-8/3
y=-2/3
--------------------------------------------------------------------------------
b)
2x-3y=10
x+y=0 /*3

2x-3y=10
3x+3y=0
------------------ dodajemy
5x=10
x=2

x+y=0
y=-x

y=-2

------------------------------------------------------


c)
3x+4y=2 /*(-5)
5x+7y=1 /*3

-15x-20y=-10
15x+21y=3
--------------- dodajemy
y=-7

5x+7*(-7)=1
5x-49=1
5x=1+49
5x=50
x=10