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2010-02-05T19:35:26+01:00
Zad. 2

a) {3/4x - 2/3y= -1/12 / *12
6x + 4y = 4

{9x -8y= -1
6x + 4y = 4 /*2

{9x - 8y =-1
12x+ 8y= 8

9x- 8y + 12x + 8y= -1 +8
21x= 7 /:21
x= 1/3

{6x +4y =4
x= 1/3

{6* 1/3 + 4y= 4
x= 1/3

{2 + 4y = 4
x= 1/3

{ 4y= 2 /:4
x=1/3

{y=1/2
x=1/3

b) {12x+ 9y =-51 /*5
10x - 5y = 25 /*9

{60x + 45y = 255
90x - 45y = 225

60x + 45y + 90x - 45y = 255 + 225
150x= 480 /:150
x= 3,2

{10x- 5y = 25
x= 3,2

{10*3,2 - 5y = 25
x= 3,2

{-5y= 25 - 32
x= 3,2

{-5y= -7 /:5
x= 3,2

{y= 7/5
x= 3,2