Question

1-Calcule:
A) {x+y=2
{x-y=-4
B) {x+y=62
{x-y=30
C) {x+y=-14
{2x-3y=38

Answer 1

A)
X = 2 - Y
X = Y - 4
2 - Y = Y - 4
6 = 2Y
Y = 3
X = 2 - 3 = -1

B)
X = 62 - Y
X = 30 + Y
62 - Y = 30 + Y
32 = 2Y
Y = 32/2 = 16
X = 30 = 16 = 46

C)
X + Y = -14  x2 -> 2X + 2Y = -28
2X - 3Y = 38
(2X + 2Y) - (2X - 3Y) = 5Y = -64
Y = -64/5 = -12,8
X = 14 - Y = -14 +12,8 = -1,2