Question

a. (1 +\(\sqrt{2}\) +\(\sqrt{5}\) )(1+\(\sqrt{2}\) - \(\sqrt{5}\))

b.\(\left(2\sqrt{2}-\sqrt{5}+3\sqrt{2}\right)\)\(\left(\sqrt{18}-\sqrt{20}+2\sqrt{2}\right)\)

c.                   \(\frac{\sqrt{9-6\sqrt{2}}-\sqrt{6}}{3}\)

Answer 1

a) \(\left(1+\sqrt{2}+\sqrt{5}\right)\left(1+\sqrt{2}-\sqrt{5}\right)\)

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

=\(1+2+2\sqrt{2}-5\)

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

nhiều quá

Answer 2

trieu dang, tớ giải dùm câu b nhé:          

b/     \(\left(2\sqrt{2}-\sqrt{5}+3\sqrt{2}\right)\left(\sqrt{18}-\sqrt{20}+2\sqrt{2}\right)\)

  \(=\left(2\sqrt{2}-\sqrt{5.1}+3\sqrt{2}\right)\left(3\sqrt{2}-2\sqrt{5}+2\sqrt{2}\right)\)         

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

  \(=60-15\sqrt{2}\)