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7 tháng 12 2024

A = \(\dfrac{3}{99.96}\) - \(\dfrac{3}{96.93}\) - \(\dfrac{3}{93.90}\) - ... - \(\dfrac{3}{7.4}\) - \(\dfrac{3}{4.1}\)

A = - (\(\dfrac{3}{1.4}\) + \(\dfrac{3}{4.7}\) + ...+ \(\dfrac{3}{90.93}\)  + \(\dfrac{3}{92.96}\)) + \(\dfrac{3}{96.99}\)

A = - (\(\dfrac{1}{1}\) - \(\dfrac{1}{4}\) + \(\dfrac{1}{4}\) - \(\dfrac{1}{7}\) + ..+ \(\dfrac{1}{90}\) - \(\dfrac{1}{93}\) + \(\dfrac{1}{93}\) - \(\dfrac{1}{96}\)) + \(\dfrac{1}{96}\) - \(\dfrac{1}{99}\)

A = - (\(\dfrac{1}{1}\) - \(\dfrac{1}{96}\)) + \(\dfrac{1}{96}\) - \(\dfrac{1}{99}\)

A = - 1 + \(\dfrac{1}{96}\) + \(\dfrac{1}{96}\)\(\dfrac{1}{99}\)

A = - \(\dfrac{95}{96}\)  + \(\dfrac{1}{96}\)\(\dfrac{1}{99}\)

A = - \(\dfrac{47}{48}\) - \(\dfrac{1}{99}\)

A = - \(\dfrac{1567}{1584}\) 

2 tháng 8 2019

an gap

17 tháng 8 2015

1) \(7.4^x=7.4^3\Leftrightarrow4^x=4^3;x=3\)

2) \(\frac{3}{2.5^x}=\frac{3}{2.5^{12}}\Leftrightarrow5^x=5^{12};x=12\)

\(2^x=2.2^8=2^9;x=9\)

4) \(5.3^x=7.3^5-2.3^5\Leftrightarrow5.3^x=3^5.\left(7-2\right)\)

\(\Leftrightarrow3^5.x=3^5.5;x=5\)

26 tháng 12 2017

bài khó thì thôi bạn ạ

26 tháng 12 2017

https://goo.gl/BjYiDy

3 tháng 1 2022

\(\dfrac{2^{15}.9^3}{6^7.4^4}\\ =\dfrac{2^{15}.3^9}{3^7.2^7.2^8}\\ =\dfrac{2^{15}.3^9}{3^7.2^{15}}\\ =\dfrac{3^9}{3^7}\\ =3^2\\ =9\)

3 tháng 1 2022

1/3

4 tháng 9 2020

a)\(\frac{6^3+3\cdot6^2+3^3}{-13}=\frac{3^3\cdot2^3+3^3\cdot2^2+3^3}{-13}=\frac{3^3\left(2^3+2^2+1\right)}{-13}=-3^3=-27\)

b) \(\frac{2^3+3\cdot2^6-4^3}{2^3+3^2}=\frac{8+3\cdot64-64}{8+9}=\frac{8+192-64}{17}=\frac{136}{17}=8\)

c) \(\frac{4^6\cdot9^5+6^9\cdot120}{8^4\cdot3^{12}-6^{11}}=\frac{2^{12}\cdot3^{10}+2^9\cdot3^9\cdot2^3\cdot3\cdot5}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}=\frac{2^{11}\cdot3^{10}\left(2+2\cdot5\right)}{2^{11}\cdot3^{10}\cdot\left(2\cdot3^2-3\right)}=\frac{12}{18-3}=\frac{12}{15}\)

d) \(\frac{5^5\cdot20^3-5^4\cdot20^3+5^7\cdot4^5}{\left(20+5\right)^3\cdot4^5}=\frac{5^5\cdot20^3-5^4\cdot20^3+20^3\cdot20^2\cdot5^2}{5^6\cdot4^5}=\frac{20^3\left(5^5-5^4+5^4\cdot4^2\right)}{20^5\cdot5}\)\(=\frac{5^4\left(5-1+16\right)}{20^2\cdot5}=\frac{5^4\cdot20}{20^2\cdot5}=\frac{5^3}{20}=\frac{5^3}{5\cdot4}=\frac{25}{4}\)

                                Bài giải

a)\(\frac{6^3+3\cdot6^2+3^3}{-13}=\frac{3^3\cdot2^3+3^3\cdot2^2+3^3}{-13}=\frac{3^3\left(2^3+2^2+1\right)}{-13}=-3^3=-27\)

b) \(\frac{2^3+3\cdot2^6-4^3}{2^3+3^2}=\frac{8+3\cdot64-64}{8+9}=\frac{8+192-64}{17}=\frac{136}{17}=8\)

c) \(\frac{4^6\cdot9^5+6^9\cdot120}{8^4\cdot3^{12}-6^{11}}=\frac{2^{12}\cdot3^{10}+2^9\cdot3^9\cdot2^3\cdot3\cdot5}{2^{12}\cdot3^{12}-2^{11}\cdot3^{11}}=\frac{2^{11}\cdot3^{10}\left(2+2\cdot5\right)}{2^{11}\cdot3^{10}\cdot\left(2\cdot3^2-3\right)}=\frac{12}{18-3}=\frac{12}{15}\)

d) \(\frac{5^5\cdot20^3-5^4\cdot20^3+5^7\cdot4^5}{\left(20+5\right)^3\cdot4^5}=\frac{5^5\cdot20^3-5^4\cdot20^3+20^3\cdot20^2\cdot5^2}{5^6\cdot4^5}=\frac{20^3\left(5^5-5^4+5^4\cdot4^2\right)}{20^5\cdot5}\)\(=\frac{5^4\left(5-1+16\right)}{20^2\cdot5}=\frac{5^4\cdot20}{20^2\cdot5}=\frac{5^3}{20}=\frac{5^3}{5\cdot4}=\frac{25}{4}\)

28 tháng 12 2017

\(\dfrac{2^{15}.9^3}{6^7.4^4}=\dfrac{2^{15}.\left(3^2\right)^3}{3^7.2^7.2^8}=\dfrac{2^{15}.3^6}{3^7.2^{15}}=\dfrac{3^6}{3^7}=\dfrac{1}{3}\)

28 tháng 12 2017

\(\dfrac{2^{15}.9^3}{6^7.4^4}=\dfrac{2^{15}.3^6}{2^{15}.3^7}=\dfrac{1}{3}\)

26 tháng 7 2020

a) \(\frac{-5}{8}\cdot\frac{11}{3}+\frac{-5}{8}\cdot\frac{1}{3}=-\frac{5}{8}\left(\frac{11}{3}+\frac{1}{3}\right)=-\frac{5}{8}\cdot4=-\frac{5}{2}\cdot1=-\frac{5}{2}\)

b) \(\frac{2}{3}+\frac{3}{4}\cdot\frac{9}{5}=\frac{2}{3}+\frac{27}{20}=\frac{121}{60}\)

c) Tương tự câu a

d) \(\frac{1}{7}\cdot\frac{3}{8}+\frac{1}{7}\cdot\frac{5}{8}=\frac{1}{7}\left(\frac{3}{8}+\frac{5}{8}\right)=\frac{1}{7}\cdot1=\frac{1}{7}\)

26 tháng 7 2020

\(a,\frac{-5}{8}.\frac{11}{3}+\frac{-5}{8}.\frac{1}{3}\)

\(=\frac{-5}{8}\left(\frac{11}{3}+\frac{1}{3}\right)\)

\(=\frac{-5}{8}.4\)

\(=\frac{-5}{2}\)

\(b,\frac{2}{3}+\frac{3}{4}.\frac{9}{5}\)

\(=\frac{2}{3}+\frac{27}{20}\)

\(=\frac{40}{60}+\frac{81}{60}\)

\(=\frac{121}{60}\)

\(c,\frac{-5}{7}.\frac{4}{9}-\frac{5}{9}.\frac{5}{7}\)

\(=\frac{-5}{7}\left(\frac{4}{9}+\frac{5}{9}\right)\)

\(=\frac{-5}{7}.1\)

\(=\frac{-5}{7}\)

\(d,\frac{1}{7}.\frac{3}{8}+\frac{1}{7}.\frac{5}{8}\)

\(=\frac{1}{7}\left(\frac{3}{8}+\frac{5}{8}\right)\)

\(=\frac{1}{7}.1\)

\(=\frac{1}{7}\)

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