Giúp em giải bài này với ạ

Bài `3`

`a)`

`A=(u-v)/(\sqrt{u}+\sqrt{v})-(\sqrt{u^3}+\sqrt{v^3})/(u-v)`

`A=((\sqrt{u}+\sqrt{v})(\sqrt{u}-\sqrt{v}))/(\sqrt{u}+\sqrt{v})-((\sqrt{u}+\sqrt{v})(u-\sqrt{uv}+v))/((\sqrt{u}+\sqrt{v})(\sqrt{u}-\sqrt{v}))`

`A=\sqrt{u}-\sqrt{v}-(u-\sqrt{uv}+v)/(\sqrt{u}-\sqrt{v})`

`A=((\sqrt{u}-\sqrt{v})^2-(u-\sqrt{uv}+v))/(\sqrt{u}-\sqrt{v})`

`A=(u-2\sqrt{uv}+v-u+\sqrt{uv}-v)/(\sqrt{u}-\sqrt{v})`

`A=(-\sqrt{uv})/(\sqrt{u}-\sqrt{v})`

`b)`

`B=(x^2-2x\sqrt{2}+2)/(x^2-2)`

`B=(x^2-2·x·\sqrt{2}+(\sqrt{2})^2)/((x-\sqrt{2})(x+\sqrt{2}))`

`B=((x-\sqrt{2})^2)/((x-\sqrt{2})(x+\sqrt{2}))`

`B=(x-\sqrt{2})/(x+\sqrt{2})`