Ta có

\(\frac{9^{15}.25^{43}}{27^{10}.5^{85}}=\frac{\left(3^2\right)^{15}.\left(5^2\right)^{43}}{\left(3^3\right)^{10}.5^{85}}=\frac{3^{30}.5^{86}}{3^{30}.5^{85}}=5\)

nhớ tick mình nha

\(\frac{9^{15}.25^{43}}{27^{10}.5^{85}}=\frac{\left(3^2\right)^{15}.\left(5^2\right)^{43}}{\left(3^3\right)^{10}.5^{85}}=\frac{3^{30}.5^{86}}{3^{30}.5^{85}}=\frac{5\left(3^{30}.5^{85}\right)}{5^{30}.5^{85}}=5\)

\(x=\frac{2^3\cdot25^2}{10^2\cdot5^3}=\frac{2^3\cdot\left(5^2\right)^2}{\left(2\cdot5\right)^2\cdot5^3}\)

    \(=\frac{2^3\cdot5^4}{2^2\cdot5^2\cdot5^3}=\frac{2^3\cdot5^4}{2^2\cdot5^5}=\frac{2}{5}\)

Vậy x = 2/5

x=2^3.25^2/10^2.5^3

x=8.625/100.125

x=5000/12500

x=10/25

x=0,4

\(x=\frac{2^3.25^2}{10^2.5^3}=\frac{2^3.5^4}{2^2.5^2.5^3}=\frac{2^3.5^4}{2^2.5^5}\)\(=\frac{2}{5}\)

giúp mk với các bạn ơi

\(\dfrac{10^2\cdot5^3}{8\cdot25^2}\)

\(=\dfrac{2^2\cdot5^2\cdot5^3}{2^3\cdot\left(5^2\right)^2}\)

\(=\dfrac{2^2\cdot5^5}{2^3\cdot5^4}\)

\(=\dfrac{5}{2}\)

Ta có

 \(C=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}...+\frac{1}{17.18}>A=\frac{1}{2.3}+\frac{1}{5.4}+...+\frac{1}{18.19}\)

\(C< =>\frac{3-2}{2.3}+\frac{4-3}{3.4}+\frac{5-4}{4.5}+...+\frac{18-17}{17.18}\)\(>A\)

\(C< =>\frac{1}{2}-\frac{1}{18}\)\(>A\)

\(C< =>\frac{4}{9}\)\(>A\left(1\right)\)

Lại có  \(C=\frac{4}{9}< \frac{9}{19}=B\left(2\right)\)

Từ (1),(2) => B>A