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9 tháng 5 2023

A =\(\dfrac{4^2}{3\times5}\) \(\times\)\(\dfrac{5^2}{4\times6}\) \(\times\) \(\dfrac{6^2}{5\times7}\) \(\times\) \(\dfrac{7^2}{6\times8}\)

A = \(\dfrac{4\times4\times5^2\times6^2\times7\times7}{3\times4\times5^2\times6^2\times7\times8}\)

A =  \(\dfrac{4}{3}\) \(\times\) \(\dfrac{7}{8}\)

A = \(\dfrac{7}{6}\) 

26 tháng 7 2017

a, \(4\times\left(-\dfrac{1}{2}\right)^3-2\times\left(-\dfrac{1}{2}\right)^2+3\times\left(-\dfrac{1}{2}\right)+1\)

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

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

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

\(=-1+1\)

\(=0\)

@Trịnh Thị Thảo Nhi

29 tháng 4 2018

a, 4×(−12)3−2×(−12)2+3×(−12)+14×(−12)3−2×(−12)2+3×(−12)+1

=(−12)[(4×−12)−(2×−12)+3]+1=(−12)[(4×−12)−(2×−12)+3]+1

=(−12)(−2+1+3)+1=(−12)(−2+1+3)+1

=(−12)2+1=(−12)2+1

=−1+1=−1+1

=0=0

8 tháng 5 2017

1,

x =( -12 . ( -3) ) : 2

x = 18

2,

a, -7/9 . 6/11 + (-2/9) = -14/33 + (-2/9) = -64/99

b, -4/7 : 2 = -4/7 . 1/2 = -2/7

c, 115 - (24 - 5. 3) = 115 - ( 24 - 15) = 115 - 9 = 106

d,= -3/7. (5/9 + 4/9) + 17/7 = -3/7 . 1 +17/7 = -3/7 . 17/7 = -51/49

e, ??? mình cx k biếtleuleu

8 tháng 5 2017

Lời giải:

\(\dfrac{x}{-12}=\dfrac{-3}{2}\)

\(\Rightarrow2x=-12.\left(-3\right)\)

\(\Rightarrow2x=36\)

\(\Rightarrow x=18\)

16 tháng 2 2023

\(C=\dfrac{5\times2^{12}\times3^8-3^9\times2^{12}}{2^2\times2^{13}\times3^8+2\times2^{12}\times\left(-3^9\right)}=\dfrac{3^8\times2^{12}\times\left(5-3\right)}{2^{15}\times3^8+2^{13}\times\left(-3\right)^9}\)

\(=\dfrac{3^8\times2^{12}\times2}{2^{13}\times3^8\times\left(4-3\right)}=\dfrac{1}{1}=1\)

\(#PaooNqoccc\)

2 tháng 4 2017

1. Tìm \(x\):

a) \(\dfrac{x}{5}=\dfrac{5}{6}+\dfrac{-19}{30}\)

\(\dfrac{x}{5}=\dfrac{1}{5}\)

\(\Rightarrow x=1\)

b) \(\dfrac{-5}{6}-x=\dfrac{7}{12}-\dfrac{1}{3}.x\)

\(\dfrac{-5}{6}-\dfrac{7}{12}=x-\dfrac{1}{3}.x\)

\(x-\dfrac{1}{3}.x=\dfrac{-17}{12}\)

\(\dfrac{2}{3}.x=\dfrac{-17}{12}\)

\(x=\dfrac{-17}{12}:\dfrac{2}{3}\)

\(x=\dfrac{-17}{8}\)

c) \(2016^3.2016^x=2016^8\)

\(2016^x=2016^8:2016^3\)

\(2016^x=2016^{8-3}\)

\(2016^x=2016^5\)

\(\Rightarrow x=5\)

d) \(\left(x+\dfrac{3}{4}\right):\dfrac{5}{2}=3\dfrac{1}{2}\)

\(\left(x+\dfrac{3}{4}\right):\dfrac{5}{2}=\dfrac{7}{2}\)

\(\left(x+\dfrac{3}{4}\right)=\dfrac{7}{2}.\dfrac{5}{2}\)

\(x+\dfrac{3}{4}=\dfrac{35}{4}\)

\(x=\dfrac{35}{4}-\dfrac{3}{4}\)

\(x=\dfrac{32}{4}=8\)

e) \(\left(2,8.x-2^5\right):\dfrac{2}{3}=3^2\)

\(\left(2,8.x-2^5\right)=9.\dfrac{2}{3}\)

\(2,8.x-2^5=6\)

\(2,8.x=6+32\)

\(2,8.x=38\)

\(x=38:2,8\)

\(x=\dfrac{95}{7}\)

f) \(\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{2}{5}\)

\(\dfrac{4}{7}.x=\dfrac{2}{5}+\dfrac{2}{3}\)

\(\dfrac{4}{7}.x=\dfrac{16}{15}\)

\(x=\dfrac{16}{15}:\dfrac{4}{7}\)

\(x=\dfrac{28}{15}\)

g) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)

\(\left(\dfrac{3x}{7}+1\right)=\dfrac{-1}{28}.\left(-4\right)\)

\(\dfrac{3x}{7}+1=\dfrac{1}{7}\)

\(\dfrac{3x}{7}=\dfrac{1}{7}-1\)

\(\dfrac{3x}{7}=\dfrac{-6}{7}\)

\(\Rightarrow3x=-6\)

\(x=\left(-6\right):3\)

\(x=-2\)

2 tháng 4 2017

2. Thực hiện phép tính:

a) \(\dfrac{1}{2}+\dfrac{1}{2}.\dfrac{2}{3}-\dfrac{1}{3}:\dfrac{3}{4}+1\dfrac{4}{5}\)

\(=\dfrac{1}{2}.\left(\dfrac{2}{3}+1\right)-\dfrac{1}{3}:\dfrac{3}{4}+\dfrac{9}{5}\)

\(=\dfrac{1}{2}.\dfrac{5}{3}-\dfrac{1}{3}:\dfrac{3}{4}+\dfrac{9}{5}\)

\(=\dfrac{5}{6}-\dfrac{4}{9}+\dfrac{9}{5}\)

\(=\dfrac{7}{18}+\dfrac{9}{5}\)

\(=\dfrac{197}{90}\)

b) \(\dfrac{7.5^2-7^2}{7.24+21}\)

\(=\dfrac{7.25-7.7}{7.24+7.3}\)

\(=\dfrac{7.\left(25-7\right)}{7.\left(24+3\right)}\)

\(=\dfrac{7.18}{7.27}\)

\(=\dfrac{2}{3}\)

c) \(\dfrac{2}{3}+\dfrac{1}{3}.\left(\dfrac{-4}{9}+\dfrac{5}{6}\right):\dfrac{7}{12}\)

\(=\dfrac{2}{3}+\dfrac{1}{3}.\dfrac{7}{18}:\dfrac{7}{12}\)

\(=\dfrac{2}{3}+\dfrac{7}{54}:\dfrac{7}{12}\)

\(=\dfrac{2}{3}+\dfrac{2}{9}\)

\(=\dfrac{8}{9}\)

a: \(=\left(\dfrac{17}{10}+\dfrac{70}{10}-\dfrac{87}{10}\right):\left(\dfrac{23}{4}-\dfrac{11}{4}+\dfrac{9}{25}\right)\cdot\left(12,98\cdot0,25\right)+12,5\)

\(=0:\left(3+\dfrac{9}{25}\right)\cdot\left(12,98+0,25\right)+12,5\)

=12,5

b: \(=\dfrac{13}{12}\cdot\dfrac{27}{5}\cdot2\cdot\dfrac{34}{9}\cdot2\cdot\dfrac{2}{17}\)

\(=\dfrac{13}{12}\cdot2\cdot\dfrac{27}{5}\cdot\dfrac{34}{9}\cdot\dfrac{4}{17}\)

\(=\dfrac{13}{6}\cdot\dfrac{27}{5}\cdot\dfrac{8}{9}=\dfrac{8}{6}\cdot3\cdot\dfrac{13}{5}=4\cdot\dfrac{13}{5}=\dfrac{52}{5}\)

26 tháng 1 2022

\(A=\dfrac{-19}{9}.\dfrac{1}{2}-\dfrac{4}{11}.\dfrac{-11}{9}+\left(-\dfrac{2}{3}\right)=-\dfrac{23}{18}\)

\(B=\left(-\dfrac{15}{6}\right):\dfrac{-1}{2}+\dfrac{7}{-12}-\dfrac{1}{3}.\dfrac{-11}{2}=\dfrac{25}{4}\)

\(C=\dfrac{3}{4}.\left(-8\right)-\dfrac{1}{3}.\dfrac{-7}{2}-\dfrac{5}{18}=-\dfrac{46}{9}\)

\(A=\dfrac{-19}{18}+\dfrac{4}{9}-\dfrac{2}{3}=\dfrac{-19}{18}+\dfrac{8}{18}-\dfrac{12}{18}=\dfrac{-23}{18}\)

\(B=\dfrac{-5}{2}\cdot\dfrac{-2}{1}-\dfrac{7}{12}+\dfrac{11}{6}=\dfrac{5\cdot12-7+22}{12}=\dfrac{75}{12}=\dfrac{25}{4}\)

 

\(B=\dfrac{\dfrac{2}{3}\left(\dfrac{17}{3}-\dfrac{4}{13}\right)+\dfrac{7}{3}}{\dfrac{9}{20}}=3:\dfrac{9}{20}=3\cdot\dfrac{20}{9}=\dfrac{60}{9}=\dfrac{20}{3}\)

9 tháng 2 2023

thanks

31 tháng 12 2022

\(C=\dfrac{4}{9}\times\dfrac{13}{17}+\dfrac{4}{17}\times\dfrac{4}{9}+\dfrac{2}{9}\\ =\dfrac{4}{9}\times\left(\dfrac{13}{17}+\dfrac{4}{17}\right)+\dfrac{2}{9}\\ =\dfrac{4}{9}\times1+\dfrac{2}{9}\\ =\dfrac{4}{9}+\dfrac{2}{9}\\ =\dfrac{6}{9}=\dfrac{2}{3}\)

\(D=\dfrac{8}{19}\times\dfrac{5}{11}+\dfrac{7}{11}\times\dfrac{8}{19}+\dfrac{12}{11}\times\dfrac{11}{19}\\ =\dfrac{8}{19}\times\left(\dfrac{5}{11}+\dfrac{7}{11}\right)+\dfrac{12}{11}\times\dfrac{11}{19}\\ =\dfrac{8}{19}\times\dfrac{12}{11}+\dfrac{12}{11}\times\dfrac{11}{19}\\ =\dfrac{12}{11}\times\left(\dfrac{8}{19}+\dfrac{11}{19}\right)\\ =\dfrac{12}{11}\times19\\ =\dfrac{12}{11}\)

31 tháng 12 2022

\(C=\dfrac{4}{9}\cdot\dfrac{13}{17}+\dfrac{4}{17}\cdot\dfrac{4}{9}+\dfrac{2}{9}\)

\(C=\dfrac{4}{9}\cdot\left(\dfrac{13}{17}+\dfrac{4}{17}\right)+\dfrac{2}{9}\)

\(C=\dfrac{4}{9}\cdot\dfrac{13+4}{17}+\dfrac{2}{9}\)

\(C=\dfrac{4}{9}\cdot\dfrac{17}{17}+\dfrac{9}{2}\)

\(C=\dfrac{4}{9}\cdot1+\dfrac{2}{9}\)

\(C=\dfrac{4}{9}+\dfrac{2}{9}\)

\(C=\dfrac{4+2}{9}\)

\(C=\dfrac{6}{9}\)

\(C=\dfrac{2}{3}\)

 

\(D=\dfrac{8}{19}\cdot\dfrac{5}{11}+\dfrac{7}{11}\cdot\dfrac{8}{19}+\dfrac{12}{11}\cdot\dfrac{11}{19}\)

\(D=\dfrac{8}{19}\cdot\left(\dfrac{5}{11}+\dfrac{7}{11}\right)+\dfrac{12}{11}\cdot\dfrac{11}{19}\)

\(D=\dfrac{8}{19}\cdot\dfrac{12}{11}+\dfrac{12}{11}\cdot\dfrac{11}{19}\)

\(D=\dfrac{12}{11}\cdot\left(\dfrac{8}{19}+\dfrac{11}{19}\right)\)

\(D=\dfrac{12}{11}\cdot\dfrac{19}{19}\)

\(D=\dfrac{12}{11}\cdot1\)

\(D=\dfrac{12}{11}\)