Odpowiedzi

Najlepsza Odpowiedź!
2010-02-22T20:43:14+01:00
A)

{ 2x - 2y = 7 |*(-2)
{ 4x - 3y = 21

{ -4x + 4y = -14
{ 4x - 3y = 21
-----------------------
y= 7

{ y=7
{ 2x - 2y =7

{ y=7
{ 2x -14 = 7 |+14

{y=7
{2x=21 |:2

{y=7
{x= 10.5


b)

{0.4x + 0.3y = 1.4 |*(-10)
{0.1x + 3y = 2.3

{-4x -3y=-14
{0.1x + 3y = 2.3
-----------------------
-3.9x = -11.7 |:(-3.9)
x= 3

{x=3
{0.1x+3y=2.3

{x=3
{y=2/3

c)
{2x+3y=14 |*3
{3x-2y = 8 |*(-2)

{6x+9y =42
{-6x+4y=-16
------------------------

13y=26 |:2
y=2

{y=2
{2x+3y=14

{y=2
[2x+6=14 |-6

{y=2
{2x=8 |:2

{y=2
{x=4

d)

{1/2x-2y=8 |*(-4)
{2x+5y =6

{-2x+8y=-32
{2x+5y=6
-----------------

13y=-26 |:13
y=-2

{y=-2
{2x+5y=6

{y=-2
{2x-10=6 |+10

{y=-2
{2x=16|:2

{y=-2
{x=8