Question

Rezolvati prin doua metode sistemul de ecuatii: {2x-y=3 {x+2y=4

Answer 1

2x-y=3 
x+2y=4

x=4-2y
2(4-2y)-y=3
8-4y-y=3
5y=5
y=1
x=4-2*1=2


metoda 2
2x-y=3 
x+2y=4      inmultim cu -2   

2x-y=3 
-2x-4y=-8
le adunam membru cu membru
0-5y=3-8
-5y=-5
y=1
x=4-2*1=2

Answer 2

{2x-y=3/2
{x+2y=4
4x-2y=6
x+2y=4
5x=10
x=2
2+2y=4
y=1