Question

1.(√20-√5)×√5
2.54 (дробь)
√6
3. √21×√14 (дробь)
√6
4. 5√11×2√2×√22

Answer 1

$\displaystyle 1) (\sqrt{20} -\sqrt{5} )\times\sqrt{5} =\sqrt{100} -\sqrt{5} ^2=10-5=5\\\\2.1) \frac{54}{\sqrt{6} } =\sqrt{\frac{2916}{6} } =\sqrt{486} =\sqrt{9\times9\times6} =9\sqrt{6} \\\\2.2) \frac{\sqrt{54} }{\sqrt{6} } =\sqrt{\frac{54}{6} } =\sqrt{9} =3\\\\3)\frac{\sqrt{21} \times\sqrt{14} }{\sqrt{6} } =\sqrt{\frac{21\times14}{6} } =\sqrt{7\times7}=7\\\\4) 5\sqrt{11} \times2\sqrt{2} \times\sqrt{22} =5\times 2\times\sqrt{11} \times\sqrt{2} \times\sqrt{22} =10\times22=220$

(мне показалось, что во 2 опечатка. записал 2 возможных решения)

Answer 2

В решении.

Объяснение:

1. (√20-√5)*√5 = √20*5 - √5*5 = √100 - √25 = 10 - 5 = 5.

2. √54 /√6  = √54/6 = √9 = 3.

3. √21*√14/√6  = √21*14/√6 = √294/6 = √49 = 7.

4. 5√11*2√2*√22 = 5√11 * 2√2*22 = 5√11 * 2√44 =

=5√11 * 2√4*11 = 5√11 * 2*2√11 = 5*4*√11*√11 = 20*11 = 220.