\(\dfrac{\left(3\cdot2^{20}+7\cdot2^{19}\right)\cdot52}{\left(13\cdot8^4\right)^2}=\dfrac{52\cdot2^{19}\cdot\left(3\cdot2+7\right)}{13^2\cdot2^{24}}\)

\(=\dfrac{2^{21}\cdot13\cdot13}{13^2\cdot2^{24}}=\dfrac{1}{2^3}=\dfrac{1}{8}\)

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tick nhéLionel Messi

ac ban giai ro ra cho mk

\(A=\frac{1}{5.6}+\frac{1}{6.7}+\frac{7}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}+\frac{1}{11.12}\)

\(A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}+\frac{1}{10}-\frac{1}{11}+\frac{1}{11}-\frac{1}{12}\)

\(A=\frac{1}{5}-\frac{1}{12}\)

\(A=\frac{7}{60}\)

\(\Rightarrow A=\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}+\frac{1}{11.12}\)

\(\Rightarrow A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+......+\frac{1}{11}-\frac{1}{12}\)

\(\Rightarrow A=\frac{1}{5}-\frac{1}{12}=\frac{12}{60}-\frac{5}{60}\)

 \(A=\frac{7}{60}\)

\(B=-\dfrac{2^{12}\cdot3^{10}+2^9\cdot2^3\cdot3^9\cdot3\cdot5}{2^{12}\cdot3^{12}+2^{11}\cdot3^{11}}\)

\(=-\dfrac{2^{12}\cdot3^{10}+2^{12}\cdot3^{10}\cdot5}{2^{11}\cdot3^{11}\cdot7}\)

\(=-\dfrac{2^{12}\cdot3^{10}\cdot6}{2^{11}\cdot3^{11}\cdot7}=-\dfrac{2^{13}\cdot3^{11}}{2^{11}\cdot3^{11}\cdot7}=\dfrac{-4}{7}\)

   120 x 123 + 373

=     41760  + 373

=        42133

Mình nhanh nhất

120 x 123 + 373

= 14760 +373 

= 15133

15133

(5+19) :3

=24 : 3

=8

=5

8