12
24
36
48
60
72
84
96
208
120
132144
156
168
180
12
24
36
48
60
72
84
96
208
120
132144
156
168
180
cho 3 so nguyen x,y,z thoa man x+y+z=0 chung minh rang x^3+y^3+z^3= 3xyz
CHUNG MING RANG (X+Y+Z)3-X3-Y3-Z3 = 3(X+Y)(Y+Z)(X+Z)
chung minh rang khong co gia tri nguyen nao cua x,y,z thoa man :x^3+y^3+x^3=x+y+z+2009
cho x,y,z duong va x+y+z=1. chung minh rang 1/x^2+2yz+1/y^2+2xz+1/z^2+2xy>=9
thank, giup minh mik cho 3 tick
cho x,y,z>0 va xyz=1 chung minh rang neu x+y+z>1/x+1/y+1/z thi trong 3 so co it nhat 1 so lon hon 1
Cho x,y,z thỏa mãn x^3-y^2-y=y^3-z^2-z=z^3-x^2-x=1/3
Chứng minh rằng x,y,z dương và x=y=z
Cho 1/x + 1/y + 1/z = 0. Chung minh xyz(1/x^3 + 1/y^3 + 1/z^3) = 3 .
Chứng minh rằng: (x+y+z)^3 - x^3 - y^3 - z^3 = 3(x+y)(y+z)(z+x)
Áp dụng: cho x+y+z = 1 , x^2 + y^2 + z^2 = . Tính B= x^2005 + y^2005 + z^2005
cho x,y,z>0 thoa man x+y+z<=1 chung minh rang 17(x+y+z)+2(1/x+1/y+1/z)=>35