Question

va rog e foarte urgent.Dau coroana va rog e FOARTE urgent.Macar cateva exercitii ca am meditatii si asta este tema va rog​

Answer 1

Răspuns:

a)

$\left \{ {{3x-7y=-20} \atop {2x+3y=2}} \right.$

inmultim prima ecuatie cu -2 si a doua cu 3

$\left \{ {{-6x+14y = 40} \atop {6x+9y=6}} \right.$

14y+9y=46

23y=46

y=2

2x+6=2

2x=-4

x=-2

b)

$\left \{ {{5x+8y=13} \atop {-2x+3y=1}} \right.$

$\left \{ {{10x+16y=26} \atop {-10x+15y=5}} \right.$

31y = 31

y=1

5x+8=13

x=1

f)

$\left \{ {{x-6y=16} \atop {-2x+9y=-23}} \right. \\\left \{ {{2x-12y=32} \atop {-2x+9y=-23}} \right.$

-12y+9y=9

-3y=9

y=-3

x-6(-3)=16

x=16-18

x=-2

g)

$\left \{ {{x+2y=5} \atop {3x-4y=-25}} \right. \\\left \{ {{-3x-6y=-15} \atop {3x-4y=-25}} \right.$

-6y-4y=-40

-10y=-40

y=4

x+8=5

x=-3

h)

$\left \{ {{3x-4y=18} \atop {2x+5y=-11}} \right. \\\left \{ {{-6x+8y=-36} \atop {6x+15y=-33}} \right.$

8y+15y=-69

23y=69

y = 3

3x-12=18

3x=30

x=10

i)

$\left \{ {{x-2(x+y)=3} \atop {y-3(x+y)=1}} \right. \\\left \{ {{-x-2y=3} \atop {-3x-2y=1}} \right. \\\left \{ {{3x-2y=-9} \atop {-3x-2y=1}} \right.$

-2y-2y=-8

-4y=-8

y=2

-x-4=3

-x=7

x=-7

Explicație pas cu pas: