Question

rozwiaz układy równan :

a

x+2y=9

y-1=3x

b

x-y=2

0.5x-1=0,25y

c.

-x-y=2

2(3x+y)=-20

d

4x+3y=54

0,33 (jedna trzecia)=4(1+ jedna ósma y)

Answer 1

a)

x+ 2y=9

y-1=3x

x=9 - 2y

y-1= 3 (9-2y)

x=9-2y

y-1= 27- 6y

x=9-2y

7y= 28 /:7

x=9-2y

y=4

 

x=9 - 8

y=4

x=1

y=4

 

b)

x-y=2

0.5x-1=0,25y

x= 2+y

0,5 (2+y) - 1= 0,25y

x=2+y

1+0,5y-1= 0,25y

x=2+y

0,25y=0

x=2

y=0

 

c)

-x-y=2

2(3x+y)= -20

-x=2+y / *(-1)

6x + 2y= -20

x= -2-y

6 ( -2-y) +2y=-20

x=-2-y

-12-6y+2y=-20

x=-2-y

-4y=-8 /:(-4)

x=-2-y

y=2

x= -2-y

y=2

x= -4

 

d)

4x + 3y= 54

1/3= 4(1+1/8y)

4x + 3y= 54

1/3= 4+ 1/2y

4x + 3y= 54

1/2y=4- 1/3 /*2

4x + 3y= 54

y= 7  i 1/3

4x + 3 * 7 i 1/3= 54

y= 7  i 1/3

4x+ 22= 54

y= 7  i 1/3

4x= 54-22

y= 7  i 1/3

4x= 32/ :4

y= 7  i 1/3

x= 8

y= 7  i 1/3