\(\frac{5^{20}}{5^{15.6}+5^{15}.19}\)

mk viết nhầm nha \(\frac{5^{20}}{5^{15.6}+5^{15.19}}=\frac{5^{20}}{5^{90}+5^{285}}\)

đúng ko

  5²⁰ : (5¹⁵.6+5¹⁵.19)

=5²⁰:[5¹⁵.(6+19)]

=5²⁰:[5¹⁵.25]

=5²⁰:[5¹⁵.5² ]

=5²⁰:[5¹⁵⁺² ]

=5²⁰ : 5¹⁷

=5^20-17

=5³

=125

chúc bạn học tốt 

=5^20:[5^15(6+9)]
=5^20:[5^15.15]
=5^20.[1/5^15.1/15)
=5^20.1/5^15.1/15
=5^20:5^15.1/15
=5^20-15.1/15
=5^5.1/15
=5^5/15
=5.5^4/5.3
=5^4/3
(=625/3)

ở dưới nhầm số 

100

20 : 5 - 2020

= 4 - 2020 

= -2016

20 : 5 - 2020

= 4 - 2020

= -2016

=4-2020

=4+(-2020)

=-2016

20 – [30 – (5 – 1)2] = 20 – (30 – 42) = 20 – (30 – 16) = 20 – 14 = 6

4 x 5 + 10 = 20 + 10 = 30

3 x 9 – 20 = 27 – 20 = 7

\(=\left(\sqrt{9.5}-\sqrt{4.5}+\sqrt{5}\right):\sqrt{6}\\ =\left(3\sqrt{5}-2\sqrt{5}+\sqrt{5}\right):\sqrt{6}\\ =\dfrac{2\sqrt{5}}{\sqrt{6}}\\ =\dfrac{\sqrt{2}.\sqrt{2}.\sqrt{5}}{\sqrt{2}.\sqrt{3}}\\ =\dfrac{\sqrt{10}}{\sqrt{3}}=\dfrac{\sqrt{30}}{3}\)

\(\left(\sqrt{45}-\sqrt{20}+\sqrt{5}\right):\sqrt{6}\\ =\left(\sqrt{9.5}-\sqrt{4.5}+\sqrt{5}\right):\sqrt{6}\\ =\left(3\sqrt{5}-2\sqrt{5}+\sqrt{5}\right):\sqrt{6}\\ =2\sqrt{5}:\sqrt{6}\\ =2\sqrt{5}.\dfrac{1}{\sqrt{6}}\\ =\dfrac{2\sqrt{5}}{\sqrt{6}}\\ =\dfrac{2\sqrt{5}.\sqrt{6}}{6}\\ =\dfrac{1}{3}.\sqrt{30}\\ =\dfrac{\sqrt{30}}{3}\)