Explicație pas cu pas: a) x + y = 5 4(x+y) = 4 × 5 = 20 ______________ b) 2 x + 2 y = 8 [ : 2 x + y = 4 3 x + 3 y = 3 × ( x + y ) = 3 × 4 = 12 ___________________________ c) x - 2 y = 5 y + 3 z = 7 [ × 2 _____________ x - 2 y = 5 2 y + 6 z = 14 ______________ adun relatiile x + 6 z = 5 + 14 x + 6 z = 19
