cho x=a/b va y=b/m voi a,b,m thuoc Z ;m>0 va x<y .Chung minh rang Z=a+b/2m thi x<Z<t
Cho x;y;z;t€Z
Chung minh (x-y)(x-z)(x-t)(y-z)(y-t)(z-t) chia het cho 12
Cach lam nua nhe
cho x, y , z la cac so nguyen thoa man x . y - x. z + y.z - z^2 +1 =0 chung minh rang x+ y =0
cho x, y , z là các số nguyen thoa man x . y - x. z + y.z - z^2 +1 =0 chung minh rang x+ y =0
cho x, y,z >0 chung minh rang\(\frac{x}{2x+y+z}+\frac{y}{2y+x+z}+\frac{z}{2z+x+y}< hoac=\frac{3}{ }4\)3/4
Chung minh rang neu 2(x+y) = 5(y+z) = 3(z+x) thi \(\frac{x-y}{4}\) \(\frac{y-z}{5}\)
Chung minh rang:
\(\frac{x}{x+y}\)+\(\frac{y}{y+z}\)+\(\frac{z}{z+x}\)< 2
cho x = a/m , y = b/m vaf x < y .hay chung to rang x<z<y voi z= a+b/2m
chox;y;z;t thuộc z
chứng minh (x-y)(x-z)(y-z)(y-t)(z-t) chia hết cho 12