Question

x + y = 1
4x + 7y = 10

Answer 1

Pelo método de adição

x + y = 1    (-4)
4x + 7y = 10

-4x - 4y = -4
4x + 7y = 10
-----------------
        3y = 6
y = 6/3
y = 2

x + y = 1
x + 2 = 1
x = 1 - 2
x = -1

$\left \{ {{x=-1} \atop{y=2}} \right.$

Answer 2

x + y = 1 . (-4)
4x + 7y = 10

-4x - 4y = -4
4x + 7y = 10
===========
3y = 6
y = 6/3
y = 2
------------
4x + 7y = 10
4x + 7.2 = 10
4x + 14 = 10
4x = 10 - 14
4x = -4
x = -4/4
x = -1

X = -1
Y = 2

s={ -1,2 }