Question

решите систему уравнений х-у=3 и 3х+2у=19

Answer 1

х - y = 3
y = x - 3
3x + 2( x - 3 ) = 19
3x + 2x - 6 = 19
5x = 25
x = 5
y = 5 - 3
y = 2
Ответ ( 5 ; 2 )

Answer 2

x-y=3. ;
3x+2y=19;=>

x=3+y
3*(3+y)+2y=19 =>

9+3y+2y=19
5y=19-9
5y=19
y=2 =>x=3+2=5