Question

resolva o sistema pelo metodo da substituicao : x+4y=-1 x-15y=-20

Answer 1

x+4y = -1        * ( -1)
x-15y = -20    * ( 1 )

-x - 4y = 1
x -15y = -20

-19y = -19
y= -19/-19
y = 1

x+4y=-1
x+4= -1
x= -4-1
x= - 5

Answer 2

x + 4y = -1
x - 15y = -20
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x = -1 - 4y

x - 15y = -20
-1 - 4y - 15y = -20
-4y - 15y = -20 + 1
-19y = -19
y = -19/-19
y = 1

x = -1 - 4y
x = -1 - 4.1
x = -1 - 4
x = -5


S={ -5, 1 }