Đáp án:
1.$(\sqrt{x}+\sqrt{y})^2=x+2\sqrt{xy}+y$
2.$(\sqrt{x}-\sqrt{y})^2=x-2\sqrt{xy}+y$
3.$(x-y)=(\sqrt{x}-\sqrt{y}).(\sqrt{x}+\sqrt{y})$
4.$\sqrt{x^3}+\sqrt{y^3}=(\sqrt{x}+\sqrt{y}).(x-\sqrt{xy}+y)$
5.$\sqrt{x^3}-\sqrt{y^3}=(\sqrt{x}-\sqrt{y}).(x+\sqrt{xy}+y)$
6.$(\sqrt{x}+\sqrt{y})^3=\sqrt{x^3}+3x\sqrt{y}+3y\sqrt{x}+\sqrt{y^3}$
7.$(\sqrt{x}-\sqrt{y})^3=\sqrt{x^3}-3x\sqrt{y}+3y\sqrt{x}-\sqrt{y^3}$
