Question

Rozwiąż trzy układy równań, kl 2 gim.

2x + y = 11
3x + 2y = 13

-3x + y = -5
5x - 2y = 7

x - 3y = 5
3x + y = -5

Answer 1

1) 2x+y=11/*(-2)
3x+2y=13

-4x-2y=-22
3x+2y=13

-x=-9
x=9
y=-2x+11
y=-18+11=-7

2) -3x+y=-5/*(2)
 5x-2y=7

-6x+2y=-10
5x-2y=7

-x=-3
x=3
y=3x-5=9-5=4

3) x-3y=5
3x+y=-5/*3

x-3y=5
9x+3y=-15

10x=-10
x=-1
y=-3x-5=3-5=-2

Answer 2

2x + y = 11 ===/*-2
3x + 2y = 13

-4x-2y = -22
3x+2y = 13

dodajesz równania do siebie, y sie skraca

-x = -9
x = 9

3*9+2y = 13
2y = 13-27
2y = -14
y = -7

2

-3x + y = -5 ==============/*2
5x - 2y = 7

-6x+2y = -10
5x-2y = 7

-x = -3
x = 3

5*3 -2y = 7
-2y = -8
y = 4

3

x-3y = 5 =========*-3
3x+y = -5 

-3x+9y = -15
3x+y = -5

10y = -20
y = -2

3x-2 = -5
3x=-3
x=-1