Question

Thực hiện phép tính:
a) \(\left(\sqrt{12}+\sqrt{3}\right)\) \(\left(\sqrt{27}-\sqrt{3}\right)\)
b)\(\left(5\sqrt{3}-2\sqrt{7}\right)\left(5\sqrt{3}+2\sqrt{7}\right)\)
-GIÚP MÌNH VỚI Ạ-

Answer 1

a) ( \(\sqrt{12}\) + \(\sqrt{3}\) ) (\(\sqrt{27}\) - \(\sqrt{3}\) )

= (\(\sqrt{3}.\sqrt{4}\) + \(\sqrt{3}\) ) ( \(\sqrt{3}.\sqrt{9}\) - \(\sqrt{3}\) )

= \(\sqrt{3}\left(\sqrt{4}+1\right)\). \(\sqrt{3}\left(\sqrt{9}-1\right)\)

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

= 3. 6 = 18

b) \(\left(5\sqrt{3}-2\sqrt{7}\right)\)\(\left(5\sqrt{3}+2\sqrt{7}\right)\)

=\(\left(5\sqrt{3}\right)^2\) \(-\left(2\sqrt{7}\right)^2\)

= 75 - 28 = 47