Question

Determine a solução do sistema
X + Y = - 4
-2X - 3Y = 9

Answer 1

x= -4 -y
-2(-4-y) -3y = 9
8 + 2y - 3y = 9
-y = 1
y= -1/ x= -4 -(-1) = -4+1 = -3
y=-1/x=-3

Answer 2

X + Y = - 4
-2X - 3Y = 9

x+y=-4
x=-4-y

-2x-3y=9
-2(-4-y)-3y=9
2y+8-3y=9
2y-3y=9-8
-y=1 (×(-1) )
y=-1

x+y= -4
x=-4-y
x=-4-(-1)
x=-4+1
x=-3

prova real: x+y=-4
-3+(-1)=-4
-2x-3y=9
-2×(-3)-3×(-1)=
6+3=9