Question

Rút gọn các biểu thức sau:

a) $C=\dfrac{1}{\sqrt{3}+\sqrt{2}-\sqrt{6}}-\dfrac{1}{\sqrt{3}+\sqrt{2}+\sqrt{6}}$;

b) $D=\left(\dfrac{\sqrt{6}-\sqrt{2}}{1-\sqrt{3}}-\dfrac{5}{\sqrt{5}}\right): \dfrac{1}{\sqrt{5}-\sqrt{2}} .$

Answer 1

a)C=\(\frac{1}{\sqrt{3}+\sqrt{2}-\sqrt{6}}\)   -\(\frac{1}{\sqrt{3}+\sqrt{2}+\sqrt{6}}\)

=\(\frac{1+\sqrt{6}}{\sqrt{3}+\sqrt{2}}-\frac{1-\sqrt{6}}{\sqrt{3}+\sqrt{2}}\)

=\(\frac{1+\sqrt{6}-1+\sqrt{6}}{\sqrt{3}+\sqrt{2}}\)

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

Answer 2

a, \(\dfrac{2\sqrt{6}\left(2\sqrt{6}+1\right)}{23}\)

b,\(-\left(\sqrt{5}+\sqrt{2}\right)\left(\sqrt{5}-\sqrt{2}\right)\)

Answer 3

a) C=2 căn 6(2căn 6+1)/23

b) D=-(căn 5+căn 2)(căn 5-căn 2)

Answer 4

C=2√6 /(√3+√2)²-6

D=-3

Answer 5

a) C=(2√6(2√6+1))/23

D= -(√5+√2)(√5-√2)

Answer 6

a. \(\dfrac{2\sqrt{6}}{\sqrt{3}+\sqrt{2}}\)

b. 

Answer 7

a) 2 can 6 ( 2 can 6 +1)/23

b) -( can 5-can 2) ( can 5-can 2)