Question

{2x-y=10
{x+5y=-17

{4a-2=b
{3a+7b=1,5

{6x-3y=9
{x+5y=-9,5

Answer 1

{2x-y=10
{x+5y=-17 -> x= -17-5y

2(-17-5y)-y=10
-34-10y-y=10
-11y=10+34
-11y=44 /:(-11)
y=4

{y=4
{x=-17-5y

x=-17-5*4
x= 3

{y=4
{x=3

Answer 2

{2x-y=10
{x+5y=-17 /*(-2)

2x-y=10
-2x-10y=34

2x-2x-y-10y=10+34
-11y=44 /(-11)
y=-4

2x-y=10
2x-(-4)=10
2x=4+10
2x=14/2
x=7

x=7
y=4


{6x-3y=9
{x+5y=-9,5 /*(-6)

6x-3y=9
-6x-30y=57

6x-6x-3y-30y=9+57
-33y=66 /(-33)
y=-2


{6x-3y=9
6x-3(-2)=9
6x+6=9
6x=-6+9
6x=3/6
x=1/3

x=1/3
y=-2

Answer 3

{2x-y=10 / ×5
{x+5y=-17
{10x-5y=50
{x+5y= -17
11x= 33/:11
x= 3

10x-5y=50
-5y=50-10x
-5y=50-10×3
-5y= 50-30
-5y=20 /:(-5)
y= -4

{x=3
{y=-4

{4a-2=b
{3a+7b=1,5
{4a-b=2 /×7
{3a+7b=1,5
{28a-7b=14
{3a+7b= 1,5
31a= 15,5 /:31
a=0,5

3a+7b= 1,5
7b= 1,5-3a
7b= 1,5 -3×0,5
7b= 1,5-1,5
7b= 0 / :7
b= 0

{a=0,5
{b=0

{6x-3y=9 /×5
{x+5y=-9,5 /×3
{30x-15y= 45
{3x+15y= -28,5
33x= 16,5 /:33
x= 0,5

30x-15y=45
-15y=45-30x
-15y= 45-30×0,5
-15y= 45-15
-15y= 30 /:(-15)
y= -2

{x=0,5
{y=-2