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5 tháng 9 2019
A = 5/7.(1+9/13) − 5/7.9/13
A= 5/7.(1+9/13 - 9/13)
A = 5/7.1
A = 5/7
B = 11/24 − 5/41 + 13/24 + 0.5 − 36/41
B = (11/24 + 13/24) - (5/41 + 36/41) + 0.5
B = 1 - 1 + 0.5
B = 0.5
C = −4/13.5/17 + (−12/13).4/17 + 4/13
C = 4/13.(-5/17) + (−12/13).4/17 + 4/13
C = 4/13.(-5/17 + 1) + (−12/13).4/17
C = 4/13.(−12/17) + (−12/13).4/17
C = (4.-12)/(13.17) + (−12/13).4/17
C = 4/17.(−12/13) + (−12/13).4/17
C = 4/17.(−12/13).2
C = 96/221
D = (4/3 − 3/2)2 − 2.∣−1/9∣ + (−5/18)
D = (4/3 − 3/2)2 − 2.1/9+ (−5/18)
D = -1/62 - 2/9+ (−5/18)
D = -1/12 - ( 2/9+ (−5/18) )
D = -1/12 - ( 4/18+ (−5/18) )
D = -1/12 - (-1/18)
D = -1/12 + 1/18
D = -3/36 + 2/36
D = -1/36
E = (−3/4 + 2/3):5/11 + (−1/4 + 1/3):5/11
E = (−3/4 + 2/3 + (−1/4) + 1/3):5/11
E = ((−3/4 + (−1/4)) + (2/3 + + 1/3)):5/11
E = ( - 1 + 1):5/11
E = 0:5/11
E = 0
26 tháng 9 2016
\(\left(\frac{\frac{17}{24}.9\frac{1}{2}-3\frac{1}{4}.\frac{17}{24}}{3\frac{1}{2}.2\frac{13}{36}+2\frac{13}{36}.2\frac{3}{4}}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{\frac{17}{24}.\left(9\frac{1}{2}-3\frac{1}{4}\right)}{2\frac{13}{36}.\left(3\frac{1}{2}+2\frac{3}{4}\right)}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{\frac{17}{24}.\left(\frac{19}{2}-\frac{13}{4}\right)}{\frac{85}{36}.\left(\frac{7}{2}+\frac{11}{4}\right)}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{\frac{17}{24}.\frac{19.2-13}{4}}{\frac{85}{36}.\frac{7.2+11}{4}}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{\frac{17}{24}.\frac{25}{4}}{\frac{85}{36}.\frac{25}{4}}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{17}{24}:\frac{85}{36}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{17}{24}.\frac{36}{85}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{3}{10}-\frac{1}{2}\right)^{-2}\)
\(=\left(\frac{3-5}{10}\right)^{-2}\)
\(=\left(\frac{-1}{5}\right)^{-2}\)
\(=\frac{1}{\left(-\frac{1}{5}\right)^2}=\frac{1}{\frac{\left(-1\right)^2}{5^2}}=\frac{1}{\frac{1}{25}}=25\)
14 tháng 12 2017
a/ \(\dfrac{11}{24}-\dfrac{5}{41}+\dfrac{13}{24}+0,5-\dfrac{36}{41}\)
\(=\left(\dfrac{11}{24}+\dfrac{13}{24}\right)+\left(-\dfrac{5}{41}-\dfrac{36}{41}\right)+0,5\)
\(=1+\left(-1\right)+0,5\)
\(=0+0,5=0,5\)
b/ \(23\dfrac{1}{4}.\dfrac{7}{5}-13\dfrac{1}{4}:\dfrac{5}{7}\)
\(=23\dfrac{1}{4}.\dfrac{7}{5}-13\dfrac{1}{4}.\dfrac{7}{5}\)
\(=\dfrac{7}{5}\left(23\dfrac{1}{4}-13\dfrac{1}{4}\right)\)
\(=\dfrac{7}{5}.10\)
\(=14\)
8 tháng 9 2015
Bài 1:
\(A=\frac{24.47-22}{24+47.23}.\frac{5+\frac{5}{7}+\frac{5}{11}-\frac{5}{13}+\frac{5}{1001}}{6+\frac{6}{7}+\frac{6}{11}-\frac{6}{13}+\frac{6}{1001}}\)\(=\frac{47.23+47-22}{24.47.23}.\frac{5\left(1+\frac{1}{7}+\frac{1}{11.}-\frac{1}{13}+\frac{1}{1001}\right)}{6\left(1+\frac{1}{7}+\frac{1}{11}-\frac{1}{13}+\frac{1}{1001}\right)}\)
\(=\frac{47.23+24}{24+47.23}.\frac{5}{6}\)
\(=1.\frac{5}{6}=\frac{5}{6}\)
Bài 2:
\(81^7-27^9-9^{13}=\left(3^4\right)^7-\left(3^3\right)^9-\left(3^2\right)^{13}\)
\(=3^{28}-3^{27}-3^{26}\)
\(=3^{22}\left(3^6-3^5-3^4\right)\)
\(=3^{22}.405\) chia hết cho 405
=>đpcm
18 tháng 12 2016
a) \(\frac{11}{24}-\frac{5}{41}+\frac{13}{24}+0,5-\frac{36}{41}\)
= \(\frac{11}{24}-\frac{5}{41}+\frac{13}{24}+\frac{1}{2}-\frac{36}{41}\)
= \(\frac{1}{2}-\left\{\frac{11}{24}+\frac{13}{24}\right\}-\left\{\frac{5}{41}+\frac{36}{41}\right\}\)
=\(\frac{1}{2}-\frac{24}{24}-\frac{41}{41}\)
=\(\frac{1}{2}-1-1\)
=\(\frac{-3}{2}\)
b) \(-12:\left\{\frac{3}{4}-\frac{5}{6}\right\}^2\)
= \(-12:\left\{\frac{9}{12}-\frac{10}{12}\right\}^2\)
= \(-12:\left\{\frac{-1}{12}\right\}^2\)
= \(-12:\frac{1}{144}\)
= \(-12.144\)
= -1728
c) \(\frac{7}{23}.\left[\left(\frac{-8}{6}\right)-\frac{45}{18}\right]\)
= \(\frac{7}{23}.\left[\left(\frac{-24}{18}\right)-\frac{45}{18}\right]\)
= \(\frac{7}{23}.\left(\frac{-23}{6}\right)\)
= \(\frac{-7}{6}\)
d) \(23\frac{1}{4}.\frac{7}{5}-13\frac{1}{4}:\frac{5}{7}\)
= \(23\frac{1}{4}.\frac{7}{5}-13\frac{1}{4}.\frac{7}{5}\)
= \(\left\{23\frac{1}{4}-13\frac{1}{4}\right\}.\frac{7}{5}\)
= \(10.\frac{7}{5}\)
= 14
e) (1+23−14).(0,8−34)2
= (1+23−14).(\(\frac{4}{5}\)−34)2
= \(\left(\frac{12}{12}+\frac{8}{12}-\frac{3}{12}\right).\left(\frac{16}{20}-\frac{15}{20}\right)^2\)
= \(\frac{17}{12}.\left(\frac{1}{20}\right)^2\)
= \(\frac{17}{20}.\frac{1}{400}\)
= \(\frac{17}{8000}\)
27 tháng 7 2019
\(\left(\frac{1}{4}-x\right)\left(x+\frac{2}{5}\right)=0\)
Ta xét 2 trường hợp
\(\begin{cases}\frac{1}{4}-x=0\\x+\frac{2}{5}=0\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{1}{4}\\x=-\frac{2}{5}\end{cases}}\)
27 tháng 7 2019
tớ mới làm bài 1 thôi bài 2 3 tớ ko có thời gian
S
23 tháng 7 2018
\(\frac{\frac{2}{3}-0,4-\frac{2}{7}+\frac{2}{11}}{\frac{13}{3}-2,6-\frac{13}{7}+\frac{13}{11}}=\frac{\frac{2}{3}-\frac{2}{5}-\frac{2}{7}+\frac{2}{11}}{\frac{13}{3}-\frac{13}{5}-\frac{13}{7}+\frac{13}{11}}=\frac{2\left(\frac{1}{3}-\frac{1}{5}-\frac{1}{7}+\frac{1}{11}\right)}{13\left(\frac{1}{3}-\frac{1}{5}-\frac{1}{7}+\frac{1}{11}\right)}=\frac{2}{13}\)
23 tháng 7 2018
\(\frac{\frac{2}{3}-0,4-\frac{2}{7}+\frac{2}{11}}{\frac{13}{3}-\frac{2}{6}-\frac{13}{7}+\frac{13}{11}}=\frac{\frac{2}{3}-\frac{2}{5}-\frac{2}{7}+\frac{2}{11}}{\frac{13}{3}-\frac{13}{5}-\frac{13}{7}+\frac{13}{11}}=\frac{2\left(\frac{1}{3}-\frac{1}{5}-\frac{1}{7}+\frac{1}{11}\right)}{13\left(\frac{1}{3}-\frac{1}{5}-\frac{1}{7}+\frac{1}{11}\right)}=\frac{2}{13}\)
Vậy \(\frac{\frac{2}{3}-0,4-\frac{2}{7}+\frac{2}{11}}{\frac{13}{3}-2,6-\frac{13}{7}+\frac{13}{11}}=\frac{2}{13}\)
Ta có: \(\frac{-2}{4}\cdot\frac{-1}{13}-\frac{-2}{24}\cdot\frac{7}{13}\)
\(=\frac12\cdot\frac{1}{13}+\frac{1}{12}\cdot\frac{7}{13}\)
\(=\frac12\cdot\frac{1}{13}+\frac{7}{13}\left(\frac12+\frac{1}{12}\right)\)
\(=\frac12\cdot\frac{1}{13}+\frac12\cdot\frac{7}{13}+\frac{1}{12}\cdot\frac{7}{13}\)
\(=\frac12\left(\frac{1}{13}+\frac{7}{13}\right)+\frac{1}{12}\cdot\frac{7}{13}=\frac12\cdot\frac{8}{13}+\frac{7}{12\cdot13}\)
\(=\frac{8}{26}+\frac{7}{12\cdot13}=\frac{4}{13}+\frac{7}{12\cdot13}\)
\(=\frac{4\cdot12+7}{12\cdot13}=\frac{48+7}{156}=\frac{55}{156}\)
\(\frac{-2}{4}.\frac{-1}{13}-\frac{-2}{24}.\frac{7}{13}\)
\(=\frac{-2}{4}.\left(\frac{-1}{13}-\frac{7}{13}\right)\)
\(=\frac{-2}{4}.\frac{-8}{3}\)
\(=\frac{16}{12}\)
\(=\frac43\)