Question

A){2x+y=5 x+2y=4
B){x-y=4 2x-y=9

Answer 1

Resposta:

A){2x+y=5

x+2y=4

$x = 4 - 2y \\ \\ 2 \times (4 - 2y) + y = 5 \\ 8 - 4y + y = 5 \\ 8 - 3y - 5 = 0 \\ 3 - 3y = 0 \\ - 3y = - 3 \times ( - 1) \\ 3y = 3 \div (3) \\ y = 1 \\ \\ x = 4 - 2y \\ x = 4 - 2 \times 1 \\ x = 4 - 2 \\ x = 2 \\ \\ (x.y) = (2.1)$

B){x-y=4

2x-y=9

$x = 4 + y \\ \\ 2 \times (4 + y) - y = 9 \\ 8 + 2y - y = 9 \\ 8 + y - 9 = 0 \\ - 1 + y = 0 \\ y = 1 \\ \\ x = 4 + y \\ x = 4 + 1 \\ x = 5 \\ \\ (x.y) = (5.1)$