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24 tháng 9 2023

`1,2×15/4+16/7×-85/8-1,2 × 5 3/4 - 16/7 × -71/8`

`=6/5xx15/4+16/7xx(-85)/8-6/5xx23/4-16/7xx(-71)/8`

`=6/5xx(15/4-23/4)+16/7xx[(-85/8)-(-71/8)]`

`=6/5xx(-8/4)+16/7xx(-14/8)`

`=-32/5`

\(B=\frac{2,5-4.\left(\frac{5}{2}-1,2\right)+\frac{3}{8}}{4.\left(\frac{5}{2}-1,2\right)-\frac{3}{5}:\frac{2}{5}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\left(\frac{25}{10}-\frac{12}{10}\right)+\frac{3}{8}}{4.\left(\frac{25}{10}-\frac{12}{10}\right)-\frac{3}{5}.\frac{5}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\frac{13}{10}+\frac{3}{8}}{4.\frac{13}{10}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-\frac{26}{5}+\frac{3}{8}}{\frac{26}{5}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{100}{40}-\frac{208}{40}+\frac{15}{40}}{\frac{52}{10}-\frac{15}{10}}-\frac{55}{148}\)

\(B=\frac{-\frac{93}{40}}{\frac{37}{10}}-\frac{55}{148}\)

\(B=\frac{93}{148}-\frac{55}{148}\)

\(B=\frac{19}{74}\)

\(A=\frac{2,5-4.\left(\frac{5}{2}-1,2\right)+\frac{3}{8}}{4.\left(\frac{5}{2}-1,2\right)-\frac{3}{5}:\frac{2}{5}}-\frac{55}{148}\)

\(A=\frac{\frac{5}{2}-4.\left(\frac{25}{10}-\frac{12}{10}\right)+\frac{3}{8}}{4.\left(\frac{25}{10}-\frac{12}{10}\right)-\frac{3}{5}.\frac{5}{2}}-\frac{55}{148}\)

\(A=\frac{\frac{5}{2}-4.\frac{13}{10}+\frac{3}{8}}{4.\frac{13}{10}-\frac{3}{2}}-\frac{55}{148}\)

\(A=\frac{\frac{5}{2}-\frac{26}{5}+\frac{3}{8}}{\frac{26}{5}-\frac{3}{2}}-\frac{55}{148}\)

\(A=\frac{\frac{100}{40}-\frac{208}{40}+\frac{15}{40}}{\frac{52}{10}-\frac{15}{10}}-\frac{55}{148}\)

\(A=\frac{-\frac{93}{40}}{\frac{37}{10}}-\frac{55}{148}\)

\(A=\frac{93}{148}-\frac{55}{148}\)

\(A=\frac{19}{74}\)

25 tháng 8 2019

\(B=\frac{2,5-4.\left(\frac{5}{2}-1,2\right)+\frac{3}{8}}{4.\left(\frac{5}{2}-1,2\right)-\frac{3}{5}:\frac{2}{5}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\left(\frac{25}{10}-\frac{12}{10}\right)+\frac{3}{8}}{4.\left(\frac{25}{10}-\frac{12}{10}\right)-\frac{3}{5}.\frac{5}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\frac{13}{10}+\frac{3}{8}}{4.\frac{13}{10}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-\frac{26}{5}+\frac{3}{8}}{\frac{26}{5}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{100}{40}-\frac{208}{40}+\frac{15}{40}}{\frac{52}{10}-\frac{15}{10}}-\frac{55}{148}\)

\(B=\frac{-\frac{93}{40}}{\frac{37}{10}}-\frac{55}{148}\)

\(B=\frac{93}{148}-\frac{55}{148}\)

\(B=\frac{19}{74}\)

a:=>3x=15

=>x=5

b: =>x+3=0,96

=>x=-2,04

c: =>x^2=36

=>x=6 hoặc x=-6

20 tháng 3 2023

`a, 3/4=(3x)/20`

`3x*4=3*20`

`3x*4=60`

`3x=60 \div 4`

`3x=15`

`x=15 \div 3`

`x=5`

`b, (1,2)/(x+3)=5/4`

`1,2*4=(x+3)*5`

`4,8=(x+3)*5`

`x+3= 4,8 \div 5`

`x+3=0,96`

`x=0,96-3`

`x=-2,04`

`c, (x^2)/32=9/8`

`x^2*8=32*9`

`x^2*8=288`

`x^2=288 \div 8`

`x^2=36`

`x^2=(+-6)^2`

`-> \text {x= 6 hoặc -6}`

12 tháng 9 2021

\(a,=\dfrac{5}{3}-\dfrac{2}{7}+\dfrac{6}{5}=\dfrac{271}{105}\\ b,=\dfrac{1}{4}+\dfrac{3}{5}-\dfrac{1}{8}+\dfrac{2}{5}-\dfrac{5}{4}=1-1-\dfrac{1}{8}=-\dfrac{1}{8}\)

12 tháng 9 2021

1a) \(\dfrac{5}{3}-\dfrac{2}{7}+1,2=\dfrac{5}{3}-\dfrac{2}{7}+\dfrac{6}{5}=\dfrac{175}{105}-\dfrac{30}{105}+\dfrac{126}{105}=\dfrac{107-30+126}{105}=\dfrac{203}{205}\)

 

10 tháng 9 2023

\(a,\left(31\dfrac{6}{13}+5\dfrac{9}{41}\right)-36\dfrac{6}{13}\\ =\left(31-36\right)+\left(\dfrac{6}{13}-\dfrac{6}{13}\right)+5\dfrac{9}{41}\\ =-5+0+5\dfrac{9}{41}\\ =\left(-5+5\right)+\dfrac{9}{41}=\dfrac{9}{41}\)

\(b,\dfrac{5}{3}+\left(-\dfrac{2}{7}\right)-\left(-1,2\right)\\ =\dfrac{5}{3}-\dfrac{2}{7}+\dfrac{6}{5}\\ =\dfrac{5.35-2.15+6.21}{105}=\dfrac{271}{105}\\ c,0,25+\dfrac{3}{5}-\left(\dfrac{1}{8}-\dfrac{2}{5}+1\dfrac{1}{4}\right)=\dfrac{1}{4}+\dfrac{3}{5}-\dfrac{1}{8}+\dfrac{2}{5}-1\dfrac{1}{4}\\ =\left(-1\dfrac{1}{4}+\dfrac{1}{4}\right)+\left(\dfrac{3}{5}+\dfrac{2}{5}\right)-\dfrac{1}{8}=-1+1-\dfrac{1}{8}=-\dfrac{1}{8}\)

10 tháng 9 2023

a) (31 6/13 + 5 9/41) - 36 6/13

= 409/13 + 214/41 - 474/13

= (409/13 - 474/13) + 214/41

= -5 + 214/41

= 9/41

b) 5/3 + (-2/7) - (-1,2)

= 5/3 - 2/7 + 6/5

= 29/21 + 6/5

= 271/105

c) 0,25 + 3/5 - (1/8 - 2/5 + 1 1/4)

= 1/4 + 3/5 - 1/8 + 2/5 - 5/4

= (1/4 - 5/4) + (3/5 + 2/5) - 1/8

= -1 + 1 - 1/8

= -1/8

a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)

\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)

\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)

\(=\dfrac{-1621}{126}\)

b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)

\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)

\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)

\(=-\dfrac{49}{20}\)