Question

Calcule os sistemas

A) x - 3y = 1
2x +5y = 13______

B) 2x + y = 10
x + 3y = 15______

C) 2x + 7y = 17
5x - y = -13________
D) 2x + y = 4
__4x - 3y = 3________

E) x + y = 2
_3x + 2y = 6________

F) x - y =5
__x +y = 7________

G) x - y =2
_2x +y = 4________

Answer 1

A)

( x - 3y = 1------>×(-2)
( 2x +5y = 13
:
:
( -2x + 6y= - 2
( 2x + 5y = 13
----------------------
11y=11
y=1


2x+5y =13
2x+5 (1)=13
2x+5=13
2x=13-5
2x=8
x=8/2
x=4

s ( 1 e 4 )


B)

(2x + y = 10--->×(-3)
(x + 3y = 15
:
:
( -6x-3y=-30
( x+3y =15
-----------------( + )
-5x= - 15
x= 3

2x+y=10
2.3+y =10
6+y =10
y=10-6
y=4


s= (3 e 4)


C)

( 2x + 7y = 17
( 5x - y = -13---->×(7)
:
:
(2x+7y=17
( y=13+5x
:
:
2x+7 (13 + 5x)=17
2x+91+ 35x=17
37x=17 -91
37x= -74
x= -2

2x+7y=17
2 (-2)+7y=17
-4+7y=17
7y=17+4
7y=21
y=3

s ( - 2 e 3 )


D)
( 2x + y = 4---->×(3)
( 4x - 3y = 3
:
:
(6x+3y=12
(4x -3y=3
------------------(+)
10x=15
x=3/2

2x+y=4
2. (1,5)+y=4
3 + y=4
y=4-3
y=1


s ( 3/2 e 1 )





E)

( x + y = 2------->(-2)
( 3x + 2y = 6
:
:
(-2x-2y= -4
(3x+2y=6
------------------(+)
x=2


-2x-2y= -4
-2 (2)-2y= -4
-4-2y= -4
-2y= -4+4
-2y=0
y=2

s (2 e 2 )


F)

(x - y =5
(x +y = 7
--------------(+)
2x=12
x=6

6-y=5
-y=5-6
y=1

s (6 e 1 )


G)

( x - y =2
( 2x +y = 4
-------------------(+)
3x=6
x=2

2(2)+y=4
4+y=4
y=4-4
y=0

s (2 e 0)