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2009-12-29T15:37:35+01:00
A)3x+2y=13
2x+y=11/*(-2)

{3x+2y=13 / (dodajemy )
{-4x-2y=-22 /
___________
-x=-9
x=9

2x+y=11
2*9+y=11
18+y=11
y=-7

{x=9
{y=-7

b)5x+3y=0/*2
-x-2y=7/*3

{10x+6y=0 /
{-3x-6y=21 /(dodajemy)
_______________
7x=21/:7
x=3

5x+3y=0
5*3+3y=0
15+3y=0
3y=-15/:3
y=-5

{x=3
{y=-5


c)3u+2v=2/*(-2)
5u+4v=6

{-6u-4v=-4/
{5u+4v=6/(dodajemy)
____________________

-u=-2/:(-1)
u=2

5u+4v=6
5*2+4v=6
10+4v=6
4v=-4
v=-1

{u=2
{v=-1

d)3s+5t=-6
1,5s-2t=-3/*(-2)

{3s+5t=-6/
{-3s+4t=6/ (dodajemy)
___________
9t=0
t=0

3s+5t=-6
3s+0=-6
3s=-6
s=-2

{t=0
{s=-2

e)5=3x-y
5x-2y=7

{-3x+y=-5/*2
{5x-2y=7

{-6x+2y=-10 /
{5x-2y=7/ (dodajemy)
____________
-x=-3
x=3

5x-2y=7
5*3-2y=7
15-2y=7
-2y=-8
y=4

{x=3
{y=4


f)x-3y=5
y+3x=-5/*3

{x-3y=5 /
{3y+9x=-15/ (dodajemy)
______________
10x=-15
x=-1,5

x-3y=5
-1,5-3y=5
-3y=6,5/:(-3)
y=-2¹/₆

{x=-1,5
{y=-2¹/₆