Question

{X+2y= 7
{X-2y= -5


{X-y= 6
{X+y= -7

Answer 1

{x+2y=7
{x-2y=-5

soma as duas

x+x+2y-2y=7-5

2x=2

x=2/2

x=1

substitui x na primeira:

x+2y=7

1+2y=7

2y=7-1

2y=6

y=6/2

y=3






{x-y=6
{x+y=-7

soma as duas:

x+x-y+y=6-7

2x=-1

x=-1/2

substitui x na primeira:

x-y=-7

$\frac{-1}{2}-y=6$

$-y=6+ \frac{1}{2}$

$-y= \frac{12}{2} + \frac{1}{2}$

$-y= \frac{13}{2}$

$y= -\frac{13}{2}$