\(a,\left(\frac{3}{4}+\frac{3}{2}\right):\frac{7}{4}-\frac{3}{4}\)

\(=\left(\frac{3}{4}+\frac{6}{4}\right).\frac{4}{7}-\frac{3}{4}\)

\(=\frac{9}{4}.\frac{4}{7}-\frac{3}{4}\)

\(=\frac{9}{7}-\frac{3}{4}\)

\(=\frac{36}{28}-\frac{21}{28}\)

\(=\frac{15}{28}\)

\(b,\left(-5\right)^2.\frac{7}{45}-\left(-5\right)^2.\frac{11}{45}\)

\(=\left(-5\right)^2.\left(\frac{7}{45}-\frac{11}{45}\right)\)

\(=\left(-5\right)^2.\frac{-4}{45}\)

\(=25.\frac{-4}{45}\)

\(=\frac{-100}{45}\)

\(=\frac{20}{9}\)

#Chúc em học tốt

BẰNG 1+56[90.;KO90

a.

\(\frac{45^{10}\times5^{20}}{75^{15}}=\frac{\left(3^2\times5\right)^{10}\times5^{20}}{\left(3\times5^2\right)^{15}}=\frac{3^{20}\times5^{10}\times5^{20}}{3^{15}\times5^{30}}=3^5=243\)

b.

\(\frac{\left(0,8\right)^5}{\left(0,4\right)^6}=\frac{\left(0,8\right)^5}{\left(0,4\right)^5}\times\frac{1}{\left(0,4\right)}=\left(\frac{0,8}{0,4}\right)^5\times\frac{1}{\frac{4}{10}}=2^5\times\frac{5}{2}=2^4\times5=16\times5=80\)

c.

\(\frac{2^{15}\times9^4}{6^6\times8^3}=\frac{2^{15}\times\left(3^2\right)^4}{\left(2\times3\right)^6\times\left(2^3\right)^3}=\frac{2^{15}\times3^8}{2^6\times3^6\times2^9}=3^2=9\)

Chúc bạn học tốt ^^

1. sai dấu nhé 

2.a, \(\frac{45^{10}.5^{20}}{75^{15}}=\frac{\left(3^2.5\right)^{10}.5^{20}}{\left(5^2.3\right)^{15}}=\frac{3^{20}.5^{30}}{5^{30}.3^{15}}=3^5=243\)

b, \(\frac{\left(0,8\right)^5}{\left(0,4\right)^6}=\frac{\left(\frac{4}{5}\right)^5}{\left(\frac{2}{5}\right)^6}=\frac{\left(\frac{2}{5}\cdot2\right)^5}{\left(\frac{2}{5}\right)^6}=\frac{\left(\frac{2}{5}\right)^5\cdot2^5}{\left(\frac{2}{5}\right)^5\cdot\frac{2}{5}}=2^5\div\frac{2}{5}=32\cdot\frac{5}{2}=80\)

c, \(\frac{2^{15}.9^4}{6^6.8^3}=\frac{2^{15}.3^8}{2^6.3^6.2^9}=\frac{2^{15}.3^2}{2^{15}}=3^2=9\)

\(M=10-3\sqrt{5}+\sqrt{45}\)

\(M=10-3\sqrt{5}+3\sqrt{5}\)

\(M=10\)

M = \(\sqrt{5.20}-\sqrt{5.3}+\sqrt{45}=\sqrt{100}-\sqrt{45}+\sqrt{45}=\sqrt{100}=10\)

=1*(1/28-1/36-1/45-1/153)

=1*125/4284

=125/4284

\(\begin{array}{l}\left( {\frac{{20}}{7}.\frac{{ - 4}}{{ - 5}}} \right) + \left( {\frac{{20}}{7}.\frac{3}{{ - 5}}} \right) = \frac{{20}}{7}.\left( {\frac{{ - 4}}{{ - 5}} + \frac{3}{{ - 5}}} \right)\\ = \frac{{20}}{7}.\left( {\frac{{ - 1}}{{ - 5}}} \right) = \frac{{20}}{7}.\frac{1}{5} = \frac{{20}}{{35}} = \frac{4}{7}\end{array}\)

=1.1.2.2.3.3.....9.9/2.2.3.3.4.4....10.10

=1/10.10

=1/100

k to nha