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14 tháng 9 2021

\(a.\dfrac{-42}{12}+\dfrac{9}{12}-\dfrac{17}{12}=-\dfrac{25}{6}\)

\(b.-\dfrac{1}{12}-\dfrac{5}{4}+\dfrac{1}{3}=-\dfrac{1}{12}-\dfrac{15}{12}+\dfrac{4}{12}=-1\)

14 tháng 9 2021

a) \(\dfrac{-7}{2}+\dfrac{3}{4}-\dfrac{17}{12}=\dfrac{-42}{12}+\dfrac{9}{12}-\dfrac{17}{12}=\dfrac{-42+9-17}{12}=-\dfrac{50}{12}=-\dfrac{25}{6}\)

b)\(-\dfrac{1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)=-\dfrac{1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)=-\dfrac{2}{24}-\left(\dfrac{63}{24}-\dfrac{8}{24}\right)\)

\(=-\dfrac{2}{24}-\dfrac{63}{24}+\dfrac{8}{24}=-\dfrac{57}{24}=-\dfrac{19}{8}\)

11 tháng 2 2018

\(B=\frac{1-\frac{1}{\sqrt{49}}+\frac{1}{49}-\frac{1}{\left(7\sqrt{7}\right)^2}}{\frac{\sqrt{64}}{2}-\frac{4}{7}+\frac{2^2}{7^2}-\frac{4}{343}}\)

\(B=\frac{1-\frac{1}{7}+\frac{1}{49}-\frac{1}{343}}{\frac{8}{2}-\frac{4}{7}+\frac{4}{49}-\frac{4}{343}}\)

\(B=\frac{\frac{343}{343}-\frac{49}{343}+\frac{7}{343}-\frac{1}{343}}{4-\frac{4}{7}+\frac{28}{343}-\frac{4}{343}}\)

\(B=\frac{\frac{300}{343}}{\frac{28}{7}-\frac{4}{7}+\frac{24}{343}}\)

\(B=\frac{\frac{300}{343}}{\frac{24}{7}+\frac{24}{343}}\)

\(B=\frac{\frac{300}{343}}{\frac{1323}{343}+\frac{24}{343}}\)

\(B=\frac{300}{343}:\frac{1347}{343}\)

\(B=\frac{100}{449}\)

11 tháng 2 2018

\(A=\frac{2^{12}.3^5-4^6.9^2}{\left(2^2.3\right)^6+8^4.3^5}-\frac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.14^3}\)

\(A=\frac{2^{12}.3^5-2^{12}.3^6}{2^{12}.3^6+2^{12}.3^5}-\frac{5^{10}.7^3-5^{10}.7^6}{5^9.7^3+5^9.2^3.7^3}\)

\(A=\frac{2^{12}.3^5\left(1-3\right)}{2^{12}.3^5.\left(3+1\right)}-\frac{5^{10}.7^3.\left(1-7^3\right)}{5^9.7^3.\left(1+8\right)}\)

\(A=\frac{-2}{4}-\frac{5.\left(-342\right)}{9}\)

\(A=\frac{-1}{2}+\frac{1710}{9}\)

\(A=\frac{-1}{2}+190\)

\(A=\frac{-1}{2}+\frac{380}{2}\)

\(A=\frac{379}{2}\)

19 tháng 4 2017

Thực hiện các phép tính:

a) 9,6.212−(2.125−1512):149,6.212−(2.125−1512):14

b) 518−1,456:725+4,5.45518−1,456:725+4,5.45;

c) (12+0,8−113).(2,3+4725−1,28)(12+0,8−113).(2,3+4725−1,28)

d) (−5).12:[(−14)+12:(−2)]+113(−5).12:[(−14)+12:(−2)]+113.

Hướng dẫn làm bài:

a) 9,6.212−(2.125−1512):149,6.212−(2.125−1512):14

=9,6.52−(250−1712)×4=9,6.52−(250−1712)×4

=4,8.5−(1000−173)=4,8.5−(1000−173)

=24−1000+173=24−1000+173

=−976+173=−976+173

=−97013=−97013

b) 518−1,456:725+4,5.45518−1,456:725+4,5.45;

=518−1,456×257+92.45=518−1,456×257+92.45

=518−0,208×25+185=518−0,208×25+185

=518−5,2+185=518−5,2+185

=25−468+32490=25−468+32490

=−11990=−11990

c) (12+0,8−113).(2,3+4725−1,28)(12+0,8−113).(2,3+4725−1,28)

=(12+45−43).(2310+10725−3225)=(12+45−43).(2310+10725−3225)

=(15+24−4030).(2310+10725−3225)=(15+24−4030).(2310+10725−3225)

=(15+24−4030).(115+214−6450)=(15+24−4030).(115+214−6450)

=−130.26550=−130.26550

=−53300=−53300

d) (−5).12:[(−14)+12:(−2)]+113(−5).12:[(−14)+12:(−2)]+113

=−60:[14+12×(−12)]+1.13=−60:[14+12×(−12)]+1.13

=−60:[−14−14]+113=−60:[−14−14]+113

=−60:(12)+113=−60:(12)+113

=120+113=120+113

=12113

19 tháng 4 2017

a) \(9,6.2\dfrac{1}{2}-\left(2.125-1\dfrac{5}{12}\right):\dfrac{1}{4}\)

\(=9,6.\dfrac{5}{2}-\left(250-\dfrac{17}{12}\right).4\)

\(=4,8.5-\left(1000-\dfrac{17}{3}\right)\)

\(=24-1000+\dfrac{17}{3}\)

\(=-976+\dfrac{17}{3}=-970\dfrac{1}{3}\)

b) \(\dfrac{5}{18}-1,456:\dfrac{7}{25}+4,5.\dfrac{4}{5}\)

\(=\dfrac{5}{18}-1,456.\dfrac{25}{7}+\dfrac{9}{2}.\dfrac{4}{5}\)

\(=\dfrac{5}{18}-0,208.25+\dfrac{18}{5}\)

\(=\dfrac{5}{18}-5,2+\dfrac{18}{5}\)

\(=-\dfrac{119}{90}\)

c) \(\left(\dfrac{1}{2}+0,8-1\dfrac{1}{3}\right).\left(2,3+4\dfrac{7}{25}-1,28\right)\)

\(=\left(\dfrac{1}{2}+\dfrac{4}{5}-\dfrac{4}{3}\right).\left(\dfrac{23}{10}+\dfrac{107}{25}-\dfrac{32}{25}\right)\)

\(=-\dfrac{1}{30}.\dfrac{265}{50}=-\dfrac{53}{300}\)

d) \(\left(-5\right).12:\left[\left(-\dfrac{1}{4}\right)+\dfrac{1}{2}:\left(-2\right)\right]+1\dfrac{1}{3}\)

\(=-60:\left[\dfrac{1}{4}+\dfrac{1}{2}.\dfrac{-1}{2}\right]+1.\dfrac{1}{3}\)

\(=-60:\left[-\dfrac{1}{4}-\dfrac{1}{4}\right]+1\dfrac{1}{3}\)

\(=-60:\left(\dfrac{1}{2}\right)+1\dfrac{1}{3}\)

\(=121\dfrac{1}{3}\)

30 tháng 9

bài1  

a) \(\dfrac{7}{6}-\dfrac{13}{12}+\dfrac{3}{4}\) 

=\(\dfrac{14}{12}-\dfrac{13}{12}+\dfrac{9}{12}\) 

=\(\dfrac{1}{12}+\dfrac{9}{12}\) 

=\(\dfrac{10}{12}=\dfrac{5}{6}\)

30 tháng 9

bài 1 

b)\(1\dfrac{1}{2}.(\dfrac{-4}{5})\) + \(\dfrac{3}{10}\) 

\(\dfrac{3}{2}.\left(-\dfrac{4}{5}\right)+\dfrac{3}{10}\) 

\(-\dfrac{6}{5}+\dfrac{3}{10}\) 

=\(-\dfrac{12}{10}+\dfrac{3}{10}\) 

=\(-\dfrac{9}{10}\) 

14 tháng 9 2021

-19/8

14 tháng 9 2021

\(\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)=-\dfrac{1}{12}-\dfrac{21}{8}+\dfrac{1}{3}=\dfrac{-2-21.3+8}{24}=-\dfrac{57}{24}=-\dfrac{19}{8}\)

15 tháng 12 2021

\(a.=\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{5}{3}+\dfrac{3}{2}+\dfrac{7}{3}-\dfrac{5}{2}=\dfrac{1+3-5}{2}-\dfrac{2+5-7}{3}=\dfrac{-1}{2}\)

\(b.\left(\dfrac{3}{4}-1\dfrac{1}{6}\right)^2:\sqrt{\dfrac{25}{144}}=\left(-\dfrac{5}{12}\right)^2:\dfrac{5}{12}=\dfrac{5}{12}\)

15 tháng 12 2021

thanks nhìu

22 tháng 10 2021

Bài 1:

a) \(\dfrac{19}{12}+\left|\dfrac{-5}{2}\right|+\left(\dfrac{3}{2}\right)^2=\dfrac{19}{12}+\dfrac{5}{2}+\dfrac{9}{4}\)

\(=\dfrac{19+5.6+9.3}{12}=\dfrac{76}{12}=\dfrac{19}{3}\)

b) \(\dfrac{2}{11}.\dfrac{16}{9}-\dfrac{2}{11}.\dfrac{7}{9}=\dfrac{2}{11}\left(\dfrac{16}{9}-\dfrac{7}{9}\right)=\dfrac{2}{11}.1=\dfrac{2}{11}\)

Bài 2:

Áp dụng t/c dtsbn:

\(\dfrac{a}{8}=\dfrac{b}{3}=\dfrac{a-b}{8-3}=\dfrac{55}{5}=11\)

\(\Rightarrow\left\{{}\begin{matrix}x=11.8=88\\b=11.3=33\end{matrix}\right.\)

23 tháng 8 2023

\(A=\left(7-\dfrac{3}{4}+\dfrac{1}{3}\right)-\left(6+\dfrac{5}{4}-\dfrac{4}{3}\right)-\left(5-\dfrac{7}{4}+\dfrac{5}{3}\right)\)

\(\Rightarrow A=7-\dfrac{3}{4}+\dfrac{1}{3}-6-\dfrac{5}{4}+\dfrac{4}{3}-5+\dfrac{7}{4}-\dfrac{5}{3}\)

\(\Rightarrow A=\left(7-6-5\right)-\dfrac{3}{4}-\dfrac{5}{4}+\dfrac{7}{4}+\dfrac{1}{3}+\dfrac{4}{3}-\dfrac{5}{3}\)

\(\Rightarrow A=-4-\dfrac{1}{4}+0\)

\(\Rightarrow A=-\dfrac{17}{4}\)

Cách 2 tính trong dấu ngoặc đơn của A, bạn tự tính nhé.

24 tháng 8 2023

A = -17/4

4 tháng 12 2017

a)\(\left|-0.75\right|+\dfrac{1}{4}-2\dfrac{1}{2}\)

=0.75+0.25-2.5

=1-2.5=-1.5

b)\(15.\dfrac{1}{5}:\left(\dfrac{-5}{7}\right)-2\dfrac{1}{5}.\left(\dfrac{-7}{5}\right)\)

=3.(-1.4)+3.08

=-4.2+3.08=-1.12

c)\(\dfrac{5}{17}+\dfrac{2}{3}-\dfrac{20}{12}+\dfrac{7}{9}+\dfrac{12}{17}\)

=\(\dfrac{49}{51}-\dfrac{5}{3}+\dfrac{7}{9}+\dfrac{12}{17}\)

=\(\dfrac{-12}{17}+\dfrac{7}{9}+\dfrac{12}{17}\)

=\(\dfrac{11}{153}+\dfrac{12}{17}\)

=\(\dfrac{7}{9}\)

d)\(\dfrac{5}{15}+\dfrac{14}{25}-\dfrac{12}{9}+\dfrac{2}{7}+\dfrac{11}{25}\)

=\(\dfrac{67}{75}-\dfrac{4}{3}+\dfrac{2}{7}+\dfrac{11}{25}\)

=-0.44+\(\dfrac{127}{175}\)

=\(\dfrac{2}{7}\)