Question

Resolva os sistemas:
A) x+y=17
-2x+3y=6

B)2x+y=-13
x-y=-2

C) -3x+2y-11
-5x-y=14

Answer 1

Olá,

Vamos lá,

A) x+y=17
-2x+3y=6

x +y=17
x=17-y

-2x+3y=6
-2(17-y)+3y=6
-34 +2y + 3y = 6
5y = 6 + 34
5y =40
y=40/5
y=8

x+y=17
x +8=17
x= 17-8
x=9
Resposta:x=9 e y=8


B)2x+y=-13
x-y=-2

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

2x+y=-13
2(-2+y)+y=-13
-4 +2y+y=-13
3y = -13 +4
3y = -9
y= -9/3
y= -3

agora acharemos x:
x-y=-2
x - (-3)=-2
x +3 = -2
x = -2-3
x=-5

Resposta: x=-5 e y=-3

C) -3x+2y=11 
-5x-y=14

-5x-y=14
-y=14 +5x   *(-1)
y = -14 -5x

-5x-y=14
-5x - (-14 -5x)=14
-5x +14 + 5x = 14
-5x +5x = 14 -14
0 = 0

y = -14 -5x
y = -14 -5*0
y = -14


Resposta:x=0 e y=-14