Question

Exercitiul 10 (B;C)

Answer 1

b)$\left \{ {{x+y=4} \atop {3x+y=6}} \right.$ ⇒ $\left \{ {{3x+3y=12} \atop {-3x-y=-6}} \right.$ ⇒ 2y= 6 ⇒ y=3
x+y=4 ⇒ x+3=4⇒ x=1
c)$\left \{ {{x-y=5} \atop {-x+3y=19}} \right.$ ⇒ 2y=24 ⇒ y=12
x-y = 5⇒x-12=5⇒x=17