Răspuns:
Explicație pas cu pas:
a) x+y=3 ->x=3-y ->x=3+2=5
x-y=7 ->3-y-y=7
-2y=7-3
-2y=4
y= -2
b) 2x+5y=8 -> 2(3+3y)+5y=8
x-3y=3 6+6y+5y=8
x=3+3y 11y=8-6
x=3+3*[tex]\frac{2}{11}[/tex] 11y=2
x=3+6/11 y=[tex]\frac{2}{11}[/tex]
x=33+6/11
x=39/11
