N
nuocmatthantien2


cho x=by+cz;y=ax+cz ,z=ax+by
xyz;x+y+z khác 0
cmr: $\dfrac{1}{a+1} +\dfrac{1}{b+1} +\dfrac{1}{c+1}$ =2
xyz;x+y+z khác 0
cmr: $\dfrac{1}{a+1} +\dfrac{1}{b+1} +\dfrac{1}{c+1}$ =2
Last edited by a moderator: