Question

Thực hiện phép tính

a, \(\frac{3}{\sqrt{5}}\)

b, \(\frac{2\sqrt{3}}{\sqrt{2}}\)

c, \(\frac{1}{\sqrt{2}+\sqrt{2}}\)

d, \(\frac{3}{\sqrt{2}-\sqrt{5}}\)

Answer 1

Lời giải:

a)

\(\frac{3}{\sqrt{5}}=\frac{3\sqrt{5}}{\sqrt{5}.\sqrt{5}}=\frac{3\sqrt{5}}{5}\)

b)

\(\frac{2\sqrt{3}}{\sqrt{2}}=\frac{2\sqrt{3}.\sqrt{2}}{2}=\sqrt{3}.\sqrt{2}=\sqrt{6}\)

c)

\(\frac{1}{\sqrt{2}+\sqrt{2}}=\frac{1}{2\sqrt{2}}=\frac{\sqrt{2}}{2.\sqrt{2}.\sqrt{2}}=\frac{\sqrt{2}}{4}\)

d)

\(\frac{3}{\sqrt{2}-\sqrt{5}}=\frac{3(\sqrt{2}+\sqrt{5})}{(\sqrt{2}-\sqrt{5})(\sqrt{2}+\sqrt{5})}=\frac{3(\sqrt{2}+\sqrt{5})}{2-5}=-(\sqrt{2}+\sqrt{5})\)