Question

Układy równań, metoda podstawiania.

2x + y =1

y = -x +4

2x - y = 4

x = 5 + y

x - y = 1

x + 2y = 4

3x - y = -4

y = 1/3x - 4/3

x + 2y = 3

2x + 3y = 7

3x + y = 5

2x + 4y = 8

-x + 3y = 4

2x + 3y = 1

2x + 2y = 1

2x - 2y = -1

Answer 1

1)2x+y=1               2) 2x-y=4                   3) x-y=1

y=x+4                        x=5+y                         x+2y=4

 

2x+x+4=1                  2(5+y)=4                    x=1+y

y=x+4                        x=5+y                        1+y +2y=4

 

3x+4=1                     10+2y=4                    x=1+y

y=x+4                        x=5+y                      3y=3

 

3x=-3                        2y=-6                     y=1

x=-1                         y=-3                        x=2

y=3                           x=2

 

 

4) 3x-y=4

y=1/3x-4/3

 

y=-4+3x

4+3x=1/3x-4/3

 

3x-1/3x=-4-4/3

2 2/3x= 2 2/3

x=1

y=-1

 

5) x+2y =3

2x+3y=7

 

x=3-2y

6-4y + 3y=7

-1y=1

y=-1

x=5

 

6)3x+y=5

2x+4y=8

 

y=5-3x

2x+ 20 -12x=8

 

20-10x=8

-10x=--12

x=1,2

y=1,4

 

7) -x+3y=4

2x+3y=1

 

x=-4+3y

-8+6y+3y=1

 

9y=9

y=1

x=-1

 

8) 2x+2y=1

2x-2y=-1

 

x+y=1/2

x-y=-1/2

 

x=1/2-y

1/2-y -y=-1/2

-2y = -1

y=1/2

x=0