Question

Rozwiąż układy równań:

a).

{5(x+3)-3(y+4)=-1

{(2x-y)-(3x+2y)=8

b).

{-2(x+y)+5(2x+y)=12

{4(y-x)+3(x-y)=-7

c).

{2(x+y)-3(x-y)=-6

{3(x+y)+4(x-y)=8

d).

{2(8y-x)-(x+y)=-15

{3(x+y)-4(4-y)=-3

Answer 1

Miałem z tego sprawdzian i dostałem "Jedyny!" 6 (ŁATWIUTKI TEN TEMAT)

a)

{5(x+3)-3(y+4)=-1

{(2x-y)-(3x+2y)=8

 

{5x+15-3y-12=-1

{2x-y-3x-2y=8

 

{5x-3y=-4

{-x-3y=8

 

{5x-3y=-4

{x=-8-3y

 

{5(-8-3y)-3y=-4

{x=-8-3y

 

{-40-15y-3y=-4

{x=-8-3y

 

{-18y=36

{x=-8-3y

 

{y=-2

{x=-8-3y

 

{y=-2

{x=-8-3(-2)

 

{y=-2

{x=-2 (ZA DUŻO TEGO xD)

 

b)

{-2(x+y)+5(2x+y)=12

{4(y-x)+3(x-y)=-7

 

{-2x-2y+10x+5y=12

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

 

{8x+3y=12

{y-x=-7

 

{8x+3y=12

{x=7+y

 

{8(7+y)+3y=12

{x=7+y

 

{56+8y+3y=12

{x=7+y

 

{11y=-44

{x=7+y

 

{y=-4

{x=7+y

 

{y=-4

{x=7-4

 

{y=-4

{x=3 (Uffff.... narzeście b zrobiłem xD)

 

c)

{2(x+y)-3(x-y)=-6

{3(x+y)+4(x-y)=8

 

{2x+2y-3x+3y=-6

{3x+3y+4x-4y=8

 

{-x+5y=-6

{7x-y=8

 

{x=6+5y

{7x-y=8

 

{x=6+5y

{7(6+5y)-y=8

 

{x=6+5y

{42+35y-y=8

 

{x=6+5y

{34y=-34

 

{x=6+5y

{y=-1

 

{x=6+5*(-1)

{y=-1

 

{x=1

{y=-1 Oojo...... ręce mnie bolą.......

 

d) OSTATNIE!!!!!!!!!!!!!!!!! :))

{2(8y-x)-(x+y)=-15

{3(x+y)-4(4-y)=-3

 

{16y-2x-x-y=-15

{3x+3y-16+4y=-3

 

{15y-3x=-15

{3x+7y-16=-3

 

{-3x=-15-15y / :(-3)

{3x+7y=13

 

{x=5+5y

{3x+7y=13

 

{x=5+5y

{3(5+5y)+7y=13

 

{x=5+5y

{15+15y+7y=13

 

{x=5+5y

{22y=-2

 

{x=5+5y

{y=-1/11

 

{x=5+5(-1/11)

{y=-1/11

 

{x=4 6/11

{y=-1/11

JUPI TERAZ DOBRZE !!!! :)))