Question

Rezolvati prin metoda substitutiei urmatorul sistem de ecuatii:{x+y=4000
{x+1000=y+200

Answer 1

{x+y egal 4000      ⇔ {x egal 4000-y               ⇔{x egal 4000-y ⇔{x egal 4000-y
{x+1000 egal y+200  {4000-y+1000 egal y+200  {-2 y egal -4800
 
⇔{x egal 4000-y   ⇔ {x egal 4000-y    ⇔ {x egal 4000-2400 ⇔   {x egal 1600
    {y egal -4800 :(-2)   {y egal 2400             {y egal 2400               {y egal 2400