Question

1) Resolva os sistemas
{x+y=7
{x-y=3

{x-y=1
{2×+5y=16

{2×+y=6
{4×+y=31

{×=y-7
{3×-y=3​

Answer 1

Explicação passo-a-passo:

a)

x+y = 7

x=7-y

 x     -   y   =   3

7-y    -   y   =   3

7-2y=3

-2y=3-7

-2y=-4

2y=4

y=4/2

y = 2

x=7-y

x=7-2

x = 5

x+y = 7

5+2=7

b)

x-y=1

x=1+y

 2x     +  5y  =  16

2(1+y)  +  5y  =  16

2+2y   +  5y  =  16

2+7y=16

7y=16-2

7y=14

y=14/7

y = 2

x=1+y

x=1+2

x = 3

x-y=1

3-2=1

c)

2x+y=6

y=6-2x

4x  +    y      =  31

4x  +  6-2x  =  31

4x-2x+6=31

2x+6=31

2x=31-6

2x=25

x=25/2

x = 12,5

y=6-2x

y=6-2(12,5)

y=6-25

y = -19

2x+y=6

2(12,5)+(-19)=6

25-19=6

d)

x=y-7

 3x    -    y    =    3

3(y-7)  -    y    =    3

3y-21-y=3

3y-y-21=3

2y-21=3

2y=3+21

2y=24

y=24/2

y=12

x=y-7

x=12-7

x=5

x=y-7

x-y=-7

5-12=-7