Question

1/✓5+✓6 +1/✓5-✓6

Answer 1

ghi lại đề dc ko ạ?

Answer 2

\(=\left(\dfrac{1}{\sqrt{5}}+\dfrac{1}{\sqrt{5}}\right)+\left(\sqrt{6}-\sqrt{6}\right)\\ =\dfrac{2}{\sqrt{5}}\)

Answer 3

`1/(\sqrt{5}+\sqrt{6})` `+` `1/(\sqrt{5}-\sqrt{6})`

`=(\sqrt{5}-\sqrt{6})/((\sqrt{5}+\sqrt{6}).(\sqrt{5}-\sqrt{6}))+(\sqrt{5}+\sqrt{6})/((\sqrt{5}+\sqrt{6}).(\sqrt{5}-\sqrt{6}))`

\(=\dfrac{\sqrt{5}-\sqrt{6}+\sqrt{5}+\sqrt{6}}{\left(\sqrt{5}+\sqrt{6}\right).\left(\sqrt{5}-\sqrt{6}\right)}\)

\(=\dfrac{2\sqrt{5}}{\left(\sqrt{5}+\sqrt{6}\right).\left(\sqrt{5}-\sqrt{6}\right)}\)

\(=\dfrac{2\sqrt{5}}{\left(\sqrt{5}\right)^2-\left(\sqrt{6}\right)^2}\)

\(=\dfrac{2\sqrt{5}}{5-6}\)

\(=-2\sqrt{5}\)