Question

sistema
2x+7y=17
5x-y=-13

Answer 1

2x+7y=17
5x-y=-13

1º) 2x+7y=17
2x= 17-7y
x= (17-7y)/2

2º)5x-y=-13
5.(17-7y)/2-y=-13
(85-35y)/2-y= -13
(85-35y-2y= -26)/2
85-35y-2y=-26
-35y-2y= -26-85
-37y= -111(-1)
+37y= +111
y= 111/37
y= 3

Voltando a primeira para achar o valor de x.
x= (17-7y)/2
x= (17-7.3)/2
x=(17-21)/2
x= -4/2
x= -2

x=-2 e y= 3