Question

Preciso muito das respostas dessas 5 questões.

Answer 1

$\left \{ {{-x+y=8} \atop {x+4y=7}} \right.$

x= 7 -4y

-(7-4y) + y= 8

y=3.

x= 7-4x3 = -5

-(-5) +3 = 8

-5+4x3=7

S= (X,Y)= (-5,3)

$\left \{ {{-y+x=15} \atop {3y-x=17}} \right.$

x= 15 + y

3y - x = 17

3y - (15 + y) = 17

y=16.

3.16 - (15+16)= 15

x= 15 +16 = 31

S= ( X,Y) = (31 , 16)

$\left \{ {{-x+y=19} \atop {x+y=1}} \right.$

y= 1 -x

-x+1-x= 19

x= -9

y= 1-(-9)

y= 10

-(-9) +10 = 19

-9+10=1

S= (X,Y)= (-9,10)

$\left \{ {{y+x=30} \atop {-y+2x=0}} \right.$

y=30-x

-y+2x=0

-(30-x) + 2x=0

x=10

y=30-10 = 20

20+10= 30

-20+2.10= 0

S=(X,Y)=(10,20)

$\left \{ {{3x+y=9} \atop {-x-y=5}} \right.$

y=9-3x

-x-y=5

-x-(9-3x)=5

x=7

y= 9-3.7= -12

3.7+(-12)= 9

-7-(-12)= 5

S=(X,Y)=(7,-12)