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8 tháng 8 2015

\(\frac{2^7.9^3}{6^5.8^2}=\frac{2^7.3^6}{3^5.2^5.2^6}=\frac{2^7.3^6}{3^5.2^{11}}=\frac{3}{2^4}=\frac{3}{16}\)

8 tháng 8 2015

\(\frac{3}{16}\)

2 tháng 10 2019

\(\frac{8^{14}}{4^4\cdot64^5}=\frac{2^{42}}{2^8\cdot2^{30}}=\frac{2^{42}}{2^{38}}=2^4=16\)

\(\frac{2^7\cdot9^3}{6^5\cdot8^2}=\frac{2^7\cdot3^6}{2^5\cdot3^5\cdot2^6}=\frac{3}{2^4}=\frac{3}{16}\)

24 tháng 6 2017

a)2/13 . 5 - 9/11 . 2/13 - 7/11 . 2/13

=2/13.(5-9/11-7/11)

=2/13.39/11

=6/11.

b)(-1/2)2 + 4,25

=1/4+4,25

=1/4+17/4

=9/2.

c)(-2/3)2 : ( --2 2/3) -- ( 5/8 -- 5/6 ) + 5.8--45/5.8

= -4/3 : -8/3 - -5/24 + 40 - 72

= -751/24.

26 tháng 4 2017

Đề hình như bị sai ban ơi sửa lại

\(A=\dfrac{3}{2.5}+\dfrac{3}{5.8}+\dfrac{3}{8.11}+...+\dfrac{3}{92.95}\)

\(A=3\left(\dfrac{1}{2.5}+\dfrac{1}{5.8}+\dfrac{1}{8.11}+...+\dfrac{1}{92.95}\right)\)

\(A=3.\dfrac{1}{3}\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{92}-\dfrac{1}{95}\right)\)

\(A=\dfrac{1}{2}-\dfrac{1}{95}\)

\(A=\dfrac{93}{190}\)

\(B=\dfrac{2}{2.5}+\dfrac{2}{5.8}+\dfrac{2}{8.11}+...+\dfrac{2}{92.95}\)

\(3B=2\left(\dfrac{1}{2.5}+\dfrac{1}{5.8}+\dfrac{1}{8.11}+...+\dfrac{1}{92.95}\right)\)

\(3B=2.\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{92}-\dfrac{1}{95}\right)\)

\(3B=2\left(\dfrac{1}{2}-\dfrac{1}{95}\right)\)

\(3B=2.\dfrac{93}{190}\)

\(3B=\dfrac{93}{95}\)

\(\Rightarrow B=\dfrac{31}{95}\)

13 tháng 6 2017

\(A=\dfrac{6^{12}.3^3.5-7.9^7.2^{13}}{2.4^7.5-2^{14}.3^2}\)

\(=\dfrac{2^{12}.3^{12}.3^3.5-7.3^{14}.2^{12}}{2.2^{14}.5-2^{14}.3^2}\)

\(=\dfrac{2^{12}.3^{15}.5-7.3^{14}.2^{13}}{2.3^{14}.5-2^{14}.3^2}\)

\(=\dfrac{2^{12}.3^{14}.\left(15-14\right)}{2^{14}.\left(2.5-3\right)}\)

\(=\dfrac{3^{14}.1}{2^2}\)

\(=\dfrac{314}{4}\)