tren tia ox lay 2 diem A va B sao cho OA=2cm,OB=6cm

a,tinh AB

b,goi m la trung diem cua OB ,trong ba diem O,A,M diem nao nam giua 2 diem con lai

tim x,y biet 12xy chia cac so 2, 3 ,5,9 deu co so du la 1

tong S =3 mu 0 cong 3mu 2cong 3mu 4 cong 3 mu 6 cong 3 mu 8 cong .......... cong 3 mu 2006 cong 3 mu 2008 tan cung bang chu so nao . vi sao