Question

РЕБЯТА СРОЧНО!!!!!!!!!!!!!!!!!!!!!!​

Answer 1

1)
{ 4x+y=12
{ 7x+2y=20

y=12-4x
2y=24-8x

7x + 24 - 8x = 20
-x=-4
x=4

16+y=12
y=-4

2)
{ x-2y=5 | •(-3)
{ 3x+8y=1

{ -3x+6y=-15
{ 3x+8y=1

-3x+3x+6y+8y=1-15
14y=-14
y=-1

x -2•(-1) = 5
x+2=5
x=3

3)
{ 4y-x=11
{ 5x-2y=17 | •2

{ 4y-x=11
{ 10x-4y=34

4y-4y+10x-x=34+11
9x = 45
x=5

4y-5=11
4y=16
y=4

4)
{ 6x-y=-1
{ 2x-3y=-11

-y=-1-6x
-3y=-3-18x

2x-18x-3=-11
-16x=-8
x=1/2

1-3y=-11
-3y=-12
y=4

5)
{ x+y=7 | •2
{ 9y-2x=-25

{ 2x+2y=14
{ 9y-2x=-25

2x-2x+9y+2y=14-25
11y=-11
y=-1

x-1=7
x=8

6)
{ 5x-3y=0
{ 15x+2y=55

5x=3y
15x=9y

9y+2y=55
11y=55
y=5

5x-3•5=0
5x=15
x=3