Răspuns:
Explicație pas cu pas:
a. x+3y = 5
x= 5-3y
3(5-3y)-2y= 4
15-9y -2y=4
11y=11 , y= 11/11 =1
x= 5-3·1 = 2 , deci x= 2 , y=1
b. 4x-y =6 , y= 4x-6
5x-2(4x-6) =6
5x-8x+12 =6
-3x=-6 , x= -6/-3 = 2
4·2 -y =6
8-y=6 , y=2
x=2 , y=2
c. x-5y =19
x= 19+5y
2(19+5y) +3y= - 1
38+10y +3y = -1
13y= -39 , y= -39/13= -3
2x+3(-3)= -1
2x-9= -1
2x=8 , x=8/2 =4
x=4 , y= -3
