A
anima416


cM 1/1/d+1/b -1/1/a+1/c <= 1/1/(a+c)+1/(b+d) voi abcd luon duong
B2: Ap dung BDT BCS de CM:
a^2b^4<= 4(a^2+b^2)^3/27 giai chi tiet dum e cai nhe
B2: Ap dung BDT BCS de CM:
a^2b^4<= 4(a^2+b^2)^3/27 giai chi tiet dum e cai nhe