Question

Rozwiąż układy równań dowolną metodą.

Answer 1

7x + 7y = 21 /:7

2x + 5y + 8 = 14

 

x + y = 3

2x + 5y = 6

 

x = 3 - y

2(3 - y) + 5y = 6

 

x = 3 - y

6 - 2y + 5y = 6

 

x = 3 - y

3y = 0 /:3

 

x = 3 - y

y = 0

 

x = 3

y = 0

 

b)

6x - 9y = 6 *(-4)

8x + 5y = 7/3 /*3

 

-24x + 36y = -24

24x + 15y = 7

-----------------------

-24x + 24x + 36y + 15y = -24 + 7

51y = -17 /:51

y = -1/3

 

6x - 9 * (-1/3) = 6

6x + 3 = 6

6x = 3 /:6

x = 3/6 = 1/2

 

 

Answer 2

{7x+7y=21 / :7

{2x+5y=14-8

 

{x+y=3

{2x+5y=6

 

{x=3-y

{2*(3-y)+5y=6

 

{x=3-y

{6-2y+5y=6

 

{x=3-y

{3y=6-6

 

{x=3-y

{y=0

 

{x=3-0

{y=0

 

{x=3

{y=0

 

 

{6x-9y=6 / :3

{8x+5y=2,3

 

{2x-3y=2 / *(-4)

{8x+5y=2,3

 

{-8x+12y=-8

{8x+5y=2,3

------------------

17y=-5,4

y=-0,32 (w zaokrągleniu)

 

-8x+12*(-0,32)=-8

-8x=-8+3,84

-8x=-4,16

x=0,52