Question

Rozwiąż:
a)
x-y=2

4x+2y= 9
b)

5x+7y=6

5x+3y=2

c)

6x+5y=21

3y=1/3+x
d)
x+3y=6
-2x+y=-5

Answer 1

a)

x-y=2    /*(-4)

4x+2y=9

 

-4x+4y=-8

4x+2y=9

_________

       6y=1

         y=1/6

x-1/6=2

x=2+1/6

x=2i1/6

b)

5x+7y=6

5x+3y=2   /*(-1)

 

5x+7y=6

-5x-3y=-2

_________

      4y=4

        y=1

5x+7*1=6

5x=6-7

5x=-1

x=-1/5

c)

6x+5y=21

3y=1/3+x

 

6x+5y=21

-x+3y=1/3   /*6

 

6x+5y=21

-6x+18y=2

____________

     23y=23

         y=1

6x+5*1=21

6x=21-5

6x=16

x=16/6

x=2i2/3

d)

x+3y=6   /*2

-2x+y=-5

 

2x+6y=12

-2x+y=-5

______________

     7y=7

       y=1

 

x+3*1=6

x=6-3

x=3

 

Answer 2

a)x-y=2  //*2        b)5x+7y=6  //*(-1)

   4x+2y=9              5x+3y=2

2x-2y=4                  -5x-7y=-6

4x+2y=9                 5x+3y=2

6x=13                     4y=4

x=2.5                      y=1

y=0.5                      x=-1/5  (minus jedna piąta)

 

d)x+3y=6//*2             c)6x+5y=21

   -2x+y=-5                   3y=1/3+x

    2x+6y=12                 6x+5y=21

    -2x=y=-5                   3y-x=1/3  //*6

    7y=7                         6x+5y=21

      y=1                          18y-6x=2

      x=3                          23y=23

                                      y=1

                                      x=2 2/3 (dwa i dwie trzecie)