Question

resolva os sistemas abaixo

( 1 ) { X+y=3
{X-y= -2

( 2 ) {2X+y= 4
{2X+y= -4

( 3 ) {Y+2X= -8
{3X+Y= -1

(4) {4-X= -Y
{2X-Y= 8

( 5 ) {2X+4= 10
{3X-2Y= 12

( 6 ) {4X+Y= 24
{X-3Y= 12

Answer 1

1.
X+y=3 
X-y= -2
-----------
2x=1
x=1/2
x+y=3
1/2+y=3
y=3-(1/2)
y=5/2

2.
2X+y= 4
2X+y= -4 ·(-1)
-------------
SI

3.
Y+2X= -8 ·(-1)
3X+Y= -1
----------------------
-2x-y=8
3x+y=-1
---------------
x=7
3x+y=-1
3·7+y=-1
21+y=-1
y=-22

4.
4-X= -Y
2X-Y= 8
------------
-x+y=-4
2x-y=8
---------------
x=4
-x+y=-4
-4+y=-4
y=0

5.
2X+4= 10
3X-2Y= 12
-----------------
2x=6  →x=3
3x-2y=12
3·3-2y=12
9-2y=12
-2y=3 ·(-1)
2y=-3
y=-3/2

6.
4X+Y= 24 ·(3)
X-3Y= 12
------------------------
13x=72
x=72/13

x-3y=12
72/13-3y=12
-3y=12-72/13
-3y=84/13 ·(-1)
y=(-84/13)/3
y=-84/39
y=28/13