Question

Zad 4 str 102

2 gimnazjum

e)

5 = 3x - y

5x - 2y = 7

f)

x-3y = 5

y + 3x = -5

Answer 1

e)

5=3x-y

5x-2y=7

 

-3x+y=-5 |*2

5x-2y=7

 

-6x+2y=-10

5x-2y=7

 

-x=-3 | *(-1)

x=3

 

5=3*3-y

5=9-y

y=9-5

y=4

 

 

 

 

f)

x-3y=5

y+3x=5

 

-3y+x=5

y+3x=5 | *3

 

-3y+x=5

3y+9x=15

 

10x=20 |:10

x=2

 

2-3y=5

-3y=5-2

-3y=3 |:3

-y=1 |*(-1)

y=-1