Question

resolva o sistema {x+y= A+B sendo A=(3) e b= (-1)
{x-y= 2A-B (-2) (5)

Answer 1

Adotando $a=\frac{3}{-2} \\ \\ b= \frac{-1}{5} \\ \\ \left \{ {{x+y= \frac{3}{-2} + \frac{-1}{5} } \atop {x-y= \frac{2.3}{-2}- \frac{-1}{5} }} \right. \\ \\ \\ \left \{ {{x+y= \frac{3}{-2} + \frac{-1}{5} } \atop {x-y= \frac{6}{-2}- \frac{-1}{5} }} \right. \\ \\ \\ \left \{ {{x+y= \frac{3}{-2} + \frac{-1}{5} } \atop {x-y= -3 + \frac{1}{5} }} \right. \\ \\ \\ \left \{ {{x+y= \frac{-17}{10} } \atop {x-y= -\frac{14}{5} }} \right.$
x = -14/5 + y
Pegamos agora, a primeira fórmula,
x + y = -17/10
(-14/5 + y) +y = -17/10
-14/5 + 2y = -17/10
2y = -17/10 +14/5
2y = 11/10
y = 11/20
Agora voltamos a substituir,
x = -14/5 + 11/20
x = -45/20