Question

Rozwiąż układy równań metodą podstawiania:

{2x+3y=4

{8x-5y=-1

{2x+9y=-9

{-3x+3y=8

Answer 1

a) {2x+3y=4 |*4

    {8x-5y=-1

 {8x+12y=16

 {8x-5y=-1

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

7y=15

y=2 1/7

 

{2x+3 * 15/7=4

y=2 1/7

 {2x*45/7=4

y=2 1/7

{2x=28/7-45/7

y=2 1/7

{2x=-17/7

y=2 1/7

x=-17/7 * 1/2

y=2 1/7

x=-17/14

y=2 1/7

x=- 1 3/14

Answer 2

{2x=4-3y/2

{8x-5y=-1

{x=2-3/2y

{8(2-3/2y)-5y=-1

{x=2-3/2y

{16-12y-5y=-1

{x=2-3/2y

{16-17y=-1

{x=2-3/2y

{-17y=-1-16

{x=2-3/2y

{-17y=-17/(-17)

{x=2-3/2y

{y=1

{x=2-3/2*1

{y=1

{x=1/2

 

{2x+9y=-9

{-3x+3y=8

{2x=-9-9y/2

{-3x+3y=8

{x=-9/2-9/2y

{-3(-9/2-9/2y)+3y=8

{x=-9/2-9/2y

{27/2+27/2y+3y=8

{x=-9/2-9/2y

{13,5+16,5y=8

{x=-4,5-4,5y

{16,5y=8-13,5

{x=-4,5-4,5y

{16,5y=-5,5/16,5

{x=-4,5-4,5y

{y=1/3

{x=-45/10-45/10*1/3

{y=1/3

{x=-19,5