x.(x+3) = 0
<=> x=0 hoặc x+3=0
<=> x=0 hoặc x=-3
(x-2).(5-x)=0
<=> x-2=0 hoặc 5-x=0
<=> x=2 hoặc x=5
a, x=0
hoặc x+3=0=>x=-3
b,x-2=0=>x=2
hoặc 5-x=0=>x=5
x.(x+3)=0
\(\Leftrightarrow\)x=0 Hoac x+3=0
\(\Leftrightarrow\)x=0 Hoac x=-3
Vay x\(\in\){0;-3)
(x-2).(5-x)=0
\(\Leftrightarrow\)x-2=0 Hoac 5-x=0
\(\Leftrightarrow\)x=2 Hoac x=5
Vay x\(\in\){2;5}