A=1/7.2/5:0=>a ko co gia tri 

a) \(\frac{8}{40}+\frac{-14}{35}-\frac{12}{60}\)

= \(\frac{1}{5}-\frac{2}{5}-\frac{1}{5}\)

= \(\left(\frac{1}{5}-\frac{1}{5}\right)-\frac{2}{5}\)

= \(-\frac{2}{5}\)

b) 5/7.5/11 + 5/7.5/11 - 5/7.14/11

= 5/7.(5/11 + 5/11 - 14/11) 

= 5/7.(-4/11)

= -20/77

c) \(19\frac{5}{8}:\frac{7}{12}-15\frac{1}{4}:\frac{7}{12}\)

= \(\left(19\frac{5}{8}-15\frac{1}{4}\right):\frac{7}{12}\)

=  \(\frac{35}{8}:\frac{7}{12}\)

=  \(\frac{15}{2}\)

d) 2/5.1/3 - 2/15 : 1/5 + 3/5.1/3

= (2/5 + 3/5).1/3 - 2/15 . 5

= 1.1/3 - 2/3

= 1/3 - 2/3

= -1/3

e) \(\frac{4}{9}.19\frac{1}{3}-\frac{4}{9}.39\frac{1}{3}\)

= \(\frac{4}{9}.\left(19\frac{1}{3}-39\frac{1}{3}\right)\)

= \(\frac{4}{9}.\left(-20\right)\)

= \(\frac{-80}{9}\)

g) \(\frac{81.17-15.81}{81.17-81.15}\)

= 1

a)8/40+-14/35-12/60=1/5+(-2/5)-1/5=-2/5

b)5/7.5/11+5/7.5/11-5/7.14/11=5/7.(5/11+5/11-14/11)=5/7.-4/11=-20/77

c)19 5/8:7/12-15 1/4:7/12=(19 5/8-15 1/4):7/12=35/8.12/7=15/2

d)2/5.1/3-2/15:1/5+3/5.1/3=2/15-2/15.5/1+3/15=2/15.2/3+1/5=-5/15=-1/5

e)4/9.19 1/3-4/9.39 1/3=4/9.(19 1/3- 39 1/3)=4/9. 20=80/9

g)81.17-15.81/81.17-81.15=81.(17-15)-15.1.17=81.2-255=162-255=-90

Chúc bạn học giỏi!!! hihi

\(\left(\frac{1}{4\cdot5-1}-\frac{1}{7\cdot5-2}\right)\text{ : }\frac{40}{77}\)

\(=\left(\frac{1}{19}-\frac{1}{32}\right)\text{ : }\frac{40}{77}\)

\(=\frac{13}{608}\text{ : }\frac{40}{77}\)

\(=\frac{1001}{24320}\)

\(a)4.6\%+7.5\%=12.1\%=0.121\)

\(b)72.5\%-27.2=0.725-27.2=-26.475\)

\(c)4.5\%\times8=36\%=0.36\)

\(\frac{8}{7}+\frac{4}{7}\cdot\left(-\frac{6}{11}\right)-\frac{4}{7}\cdot\frac{5}{11}\)

\(=\frac{8}{7}+\frac{4}{7}\cdot\left(-\frac{6}{11}-\frac{5}{11}\right)\)

\(=\frac{8}{7}-\frac{4}{7}\)

\(=\frac{4}{7}\)

thế còn con nữa đâu bạn

\(\frac{8}{7}+\frac{4}{7}.\left(-\frac{6}{11}\right)-\frac{4}{7}.\frac{5}{11}\)

\(=\frac{8}{7}+\frac{4}{7}.\left(-\frac{6}{11}-\frac{5}{11}\right)\)

\(=\frac{8}{7}-\frac{4}{7}.-1\)

\(=\frac{8}{7}+\frac{4}{7}\)

\(=\frac{12}{7}\)

\(\dfrac{1}{2}\) \(\times\) \(\dfrac{6}{7}\) + \(\dfrac{5}{7\times5}\) - \(\dfrac{8}{9}\)

= \(\dfrac{3}{7}\) + \(\dfrac{1}{7}\) - \(\dfrac{8}{9}\)

= \(\dfrac{4}{7}\) - \(\dfrac{8}{9}\)

= - \(\dfrac{20}{63}\)

\(\dfrac{20}{63}\)

= 20/63 nha bn 

(-12.\(\dfrac{2}{7}\) + \(\dfrac{8}{9}\): 3\(\dfrac{1}{2}\) - \(\dfrac{2}{7}\).\(\dfrac{5}{18}\)). 3\(\dfrac{1}{2}\)

(-\(\dfrac{24}{7}\) +  \(\dfrac{8}{9}\):\(\dfrac{7}{2}\) - \(\dfrac{5}{63}\)). \(\dfrac{7}{2}\)

= (-\(\dfrac{24}{7}\) + \(\dfrac{16}{63}\) - \(\dfrac{5}{63}\)).\(\dfrac{7}{2}\)

= (\(-\dfrac{216}{63}\) + \(\dfrac{16}{63}\) - \(\dfrac{5}{63}\)). \(\dfrac{7}{2}\)

=  - \(\dfrac{205}{63}\). \(\dfrac{7}{2}\)

= - \(\dfrac{205}{18}\) 

{ x² - [ 6² - ( 8² -9.7 )³ -7.5 ]³ -5.3 }³ =1 ... {x² - [6² - 1³ -7.5]³ - 5.3}³=1. {x² - [36 - 1 -7.5]³ - 5.3}³=1. {x² - [36 - 1 - 35]³ - 5.3}³=1. {x² - [35 - 35]³ -5.3}³=1. {x² - 0³ - 5.3}³=1. {x² - 0 -5.3}³=1. {x² - 0 - 15}³=1. {x.x - 0 - 15}³=1. {x.x + 0+15}³=1. {x.x +15}³=1.