Question

Rezolvati sistemele:
7x-y=-4
2x-3y=-11

2(x-3y)+7=9
5x-12=6y+2

Va rog frumos repede

Answer 1

1){7x-y=-4 |×(-3)
2x-3y=-11

{-21x+3y=12
2x-3y=-11

-19x=1 |×(-1)
19x=-1
x=-1/19

2x-3y=-11
2×(-1/19)-3y=-11
-2/19-3y=-11 |×19
-2-57y=-209
-57y=-209+2
-57y=-207 |:(-3)
19y=69
y=69/19

2){2(x-3y)+7=9
5x-12=6y+2

{2x-6y+7=9
5x-6y=2+12

{2x-6y=9-7
5x-6y=14

{2x-6y=2 |×(-1)
5x-6y=14

{-2x+6y=-2
5x-6y=14

3x=-12
x=-12/3
x=-4
-2x+6y=-2
-2×(-4)+6y=-2
8+6y=-2
6y=-2-8
6y=-10
y=-10/6
y=-5/3