Question

3) calcule o valor de x e y ?
{3×+5y=7
{×-y=5
??Qual a resposta ??

Answer 1

{3×+5y=7
{×-y=5 

×-y=5 
x=y+5

3×+5y=7
3(y+5)+5y=7
3y+15+5y=7
8y=7-15
y=-8/8
y=-1

×-y=5
x-(-1)=5
x+1=5
x=5-1
x=4

resposta: x=4   y=-1