Question

Rozwiąż układ równań.

2x-y=8 x+y=20 4x+y=0
x-3y= -1 x-y=10 x-y=-3

Answer 1

2x-y=8

x-3y = -1 mnozymuy to równanie *-2

 

2x-y =8

-2x+6y = 2

 

5x=10

y = 2

 

2x - 2 = 8

2x=10

x = 5

 

sprawdzam

 

5-3*2 = 5-6 = -1

 

x+y = 20

x-y = 10

 

2x=30

x=15

 

15+y = 20

y = 20-15

y = 5

 

sprawdzam

 

15-5 = 10

 

4x+y = 0

x-y = -3

 

5x = -3

x = -3/5 = -0,6

 

 

-0,6 -y = -3

-y = -2,4

y = 2,4

 

sprawdzam

 

4*(-0,6) +2,4 = 0

-2,4+2,4 = 0

 

 

 

Answer 2

2x-y=8

x-3y=-1

 

2x-y=8

x=-1+3y

 

2(-1+3y)-y=8

x=-1+3y

 

-2+6y-y=8

x=-1+3y

 

6y-y=8+2

x=-1+3y

 

5y=10/: 5

x=-1+3y

 

y=2

x=-1+3·2

 

y=2

x=-1+6

 

y=2

x=5

 

 

 

x+y=20

x-y=10

 

x=20-y

20-y-y=10

 

x=20-y

-y-y=10-20

 

x=20-y

-2y=-10/: (-2)

 

x=20-y

y=5

 

x=20-5

y=5

 

x=15

y=5

 

 

 

4x+y=0

x-y=-3

 

y=-4x

x-(-4x)=-3

 

y=-4x

x+4x=-3

 

y=-4x

5x=-3/:5

 

y=-4x

x=-⅗

 

y=-4·(-⅗)

x=-⅗

 

y=¹²/₅

x=-⅗

 

y=2⅖

x=-⅗