Question

Resolva com o método da substituição: a){x+5y=-9 3x-2y=7 b){x-4y=8 3x+2y=10 c) {x+2y=0 3x-y=7 d) {3x+y=-6 x-7y=-2 e) {x+5y=1 2x+y=11 f){3x+y=1 x+4y=-7 g){x+3y=10 5x+2y=-2 h){2x+3y=0 x-y=5 i){y-3x=0 x+2y=-1

Answer 1

a) x+5y= -9 x= -9-5y

3x-2y= 7

3(-9-5y)-2y= 7

-27-15y-2y= 7

-15y-2y= 7+27

-17y= 34

y= 34/-17

y= -2

x= -9-5.(-2)

x= -9+10

x= 1

b) x-4y=8 x= 8+4y

3x+2y=10

3(8+4y)+2y= 10

24+12y+2y= 10

24+14y= 10

14y= 10-24

14y= -14

y= -14/14

y= -1

x= 8+4(-1)

x= 8-4

x= 4

c) x+2y=0 x= 0-2y

3x-y=7

3(0-2y)-y= 7

0-6y-y= 7

-7y= 7-0

-7y= 7

y= 7/-7

y= -1

x= 0-2(-1)

x= 0+2

x= 2

d) 3x+y=-6 y= -6-3x

x-7y=-2

x-7(-6-3x)= -2

x+42+21x= -2

22x= -2-42

22x= -44

x= -44/22

x= -2

y= -6-3(-2)

y= -6+6

y= 0

e) x+5y=1 x= 1-5y

2x+y=11

2(1-5y)+y= 11

2-10y+y= 11

-9y= 11-2

-9y= 9

y= 9/-9

y= -1

x= 1-5.-1

x= 1+5

x= 6

f) 3x+y=1 y= 1-3x

x+4y=-7

x+4(1-3x)= -7

x+4-12x= -7

x-12x= -7-4

-11x= -11

x= -11/-11

x= 1

y= 1-3.1

y= 1-3

y= -2

g) x+3y=10 x= 10-3y

5x+2y=-2

5(10-3y)+2y= -2

50-15y+2y= -2

-13y= -52

y= -52/-13

y= 4

x= 10-3.4

x= 10-12

x= -2

h) 2x+3y=0

x-y=5 x= 5+y

2(5+y)+3y= 0

10+2y+3y= 0

10+5y= 0

5y= 0-10

5y= -10

y= -10/5

y= -2

x= 5+(-2)

x= 5-2

x= 3

i) y-3x=0

x+2y= -1 x= -1-2y

y-3(-1-2y)= 0

y+3+6y= 0

7y= -3

y= -3/7

x= -1-2(-3/7)

x= -1+6/7

x= -1/7

espero ter ajudado