Question

1-Resolva os sistemas abaixo:

Através do método da adicão:

A)x-y=2
2x+y=4

B)x+y=7
x-y=1

C)x+y=11
x-y=3

D)x-y=16
x+y=74

E)x-y=1
x+y=9

F)2x-y=20
2x+y=48

Answer 1

a) x-y=2
2x+y=4 (cancela -y com o +y)
x+2x=2+4
3x=6
x=2
x-y=2
2-y=2
y=0

b) x+y=7
x-y=1 (cancela o +y com o -y)
x+x=7+1
2x=8
x=4

x+y=7
4+y=7
y=3

c) x+y=11
x-y=3 (cancela o +y com o -y)
x+x=11+3
2x=14
x=7

x+y=11
7+y=11
y=4

d) x-y=16
x+y=74 (cancela -y com +y)
2x=90
x=45

x+y=74,
45+y=74
y=29

e)x-y=1
x+y=9 (cancela o -y com +y)
2x=10
x=5

x+y=9
5+y=9
y=9-5
y=4

f) 2x-y=20
2x+y=48 (cancela -y com +y)
4x=68
x=17

2x+y=48
2*17+y=48
y=48-34
y=14