cho 3 so nguyen x,y,z thoa man x+y+z=0 chung minh rang x^3+y^3+z^3= 3xyz
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
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
\(\Leftrightarrow\left(x^3-x\right)+\left(y^3-y\right)+\left(z^3-z\right)=2009\Leftrightarrow\left(x-1\right)x\left(x+1\right)+\left(y-1\right)y\left(y+1\right)+\left(z+1\right)z\left(z+1\right)=2009\)
Ta thấy về trái chia hết cho 3, vế phải không chia hết cho 3 =>đpcm.
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 cac so x,y,z khac 0 va thoa man \(\frac{1}{x}+\frac{1}{y}+\frac{1}{z}=0\) Chung minh rang x2(y+z)+y2(z+x ) +z2(x+z)+3xyz
ai nnha nhat minh tik dung luon
cho x,y,z la cac so nguyen duong va x+y+z la so le, cac so thuc a,b,c thoa man (a-b)/x=(b-c)/y=(a-c)/z. chung minh rang a=b=c
cho x,y,z la 3 so thuc tuy y thoa man x+y+z=0 va -1< x<1,-1<y<1,-1<z<1.chung minh rang da thuc x^2+y^4+z^6 co gia tri khong lon hon 2
Cho x,y,z la 3 so nguyen duong, nguye to cung nhau thoa man (x-z)(y-z)=z^2. Chung minh tich xyz la so chinh phuong
Giai nhanh jum mik nha dg can gap
cho cac so x,y,z thoa man x/2013=y/2014=z/2015 chung minh rang 4(x-y)(y-z)=(z-x)^2
cho x;y;z;t la 4 so khac 0 va thoa man cac dieu kien sau:
y^2=xz, z^2=yt, vay^3+z^3+t^3kac 0chung minh rang:
(y^3+z^3+x^3)/y^3+z^3+t^3=x/t