Question

Answer 1

Bài 2:

\(x-\sqrt{xy}-2y=0\)

=>\(x-2\sqrt{xy}+\sqrt{xy}-2y=0\)

=>\(\sqrt{x}\left(\sqrt{x}-2\sqrt{y}\right)+\sqrt{y}\left(\sqrt{x}-2\sqrt{y}\right)=0\)

=>\(\left(\sqrt{x}-2\sqrt{y}\right)\left(\sqrt{x}+\sqrt{y}\right)=0\)

=>\(\sqrt{x}-2\sqrt{y}=0\)

=>\(\sqrt{x}=2\sqrt{y}=\sqrt{4y}\)

=>x=4y

\(Q=\frac{x^3+y^3}{\left(x+2y\right)^3}\)

\(=\frac{\left(4y\right)^3+y^3}{\left(4y+2y\right)^3}=\frac{64y^3+y^3}{\left(6y\right)^3}=\frac{65y^3}{216y^3}=\frac{65}{216}\)