Question

Se x+y=18
e x-y=4
qual o valor de x e y?

Answer 1

x+y=18
x-y=4

x=18-y

18-y-y=4
14=2y
7=y

x+7=18
x=18-7
x=11

x-7=4
x=4+7
x=11

Answer 2

x+y=18
x-y=4

2x = 22
x=22/2
X =11


substituir na 1*
x+y=18
11+y=18
y=18-11
y=7

s={(11 ; 7)}