Question

Alguém sabe a resposta?
-x+5y=7
5×-5y=5

Answer 1

$\left\{\begin{array}{cc}-x\cancel{+5y}=7\\5x\cancel{-5y}=5\\\end{array}\right$

4x = 12

x = 12/4

x = 3

$\left\{\begin{array}{cc}-3+5y=7\\x=3\\\end{array}\right$$\left\{\begin{array}{cc}5y=7+3\\x=3\\\end{array}\right$$\left\{\begin{array}{cc}5y=10\\x=3\\\end{array}\right$$\left\{\begin{array}{cc}y=\frac{10}{5}\\x=3\\\end{array}\right$$\left\{\begin{array}{cc}y=2\\x=3\\\end{array}\right$

Answer 2

-x+5y=7

5×-5y=5

isto é um sistema

-x + 5y = 7

x - y = 1

soma

4y = 8

y = 8/4 = 2

substitue o y em uma equaçao

x - 2 = 1

x = 3

S = (3, 2)