\(B=\dfrac{13}{15}\cdot0,15\cdot3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):\left(1\dfrac{23}{24}\right)\)

\(=\dfrac{13}{15}\cdot\dfrac{15}{100}\cdot3+\left(\dfrac{32}{60}-1-\dfrac{19}{60}\right):\dfrac{47}{24}\)

\(=\dfrac{39}{100}+\dfrac{-47}{60}\cdot\dfrac{24}{47}\)

\(=\dfrac{39}{100}-\dfrac{24}{60}=\dfrac{39}{100}-\dfrac{40}{100}=-\dfrac{1}{100}\)

Giải:

\(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\)

\(=\dfrac{28}{15}.\dfrac{1}{4}.3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right):\dfrac{47}{24}\)

\(=\dfrac{7}{5}+\left(-\dfrac{47}{60}\right).\dfrac{24}{47}\)

\(=\dfrac{7}{5}+\left(-\dfrac{2}{5}\right)\)

\(=\dfrac{7}{5}-\dfrac{2}{5}\)

\(=1\)

Vậy ...

Cảm ơn nha

đọc mà phát choáng

\(1\dfrac{13}{15}\cdot\left(0,5\right)^2+3\cdot\left(\dfrac{8}{15}+1\dfrac{19}{60}\right):1\dfrac{23}{24}\)

\(=\dfrac{28}{15}\cdot\dfrac{1}{4}+3\cdot\left(\dfrac{8}{15}+\dfrac{79}{60}\right):\dfrac{47}{24}\)

\(=\dfrac{7}{15}+3\cdot\dfrac{37}{20}\cdot\dfrac{24}{47}\)

\(=\dfrac{7}{15}+\dfrac{666}{235}=\dfrac{2327}{705}\)

\(1\dfrac{13}{15}.\left(0,5\right)^2+3.\left(\dfrac{8}{15}+1\dfrac{19}{60}\right):1\dfrac{23}{24}\) 

\(=\dfrac{28}{15}.\dfrac{1}{4}+3.\left(\dfrac{8}{15}+\dfrac{79}{60}\right):\dfrac{47}{24}\) 

\(=\dfrac{7}{15}+3.\dfrac{37}{20}:\dfrac{47}{24}\) 

\(=\dfrac{7}{15}+\dfrac{666}{235}\) 

\(=\dfrac{2327}{705}\)

b: Ta có: \(1\frac{13}{15}\cdot\left(0,5\right)^2\cdot3+\left(\frac{8}{15}-1\frac{19}{60}\right):1\frac{23}{24}\)

\(=\frac{28}{15}\cdot3\cdot\frac14+\left(\frac{8}{15}-\frac{79}{60}\right):\frac{47}{24}\)

\(=\frac{28}{5}\cdot\frac14+\left(\frac{32}{60}-\frac{79}{60}\right)\cdot\frac{24}{47}=\frac75+\frac{-47}{60}\cdot\frac{24}{47}\)

\(=\frac75-\frac25=\frac55=1\)

c: \(\left(-2\right)^3\cdot\frac{-1}{24}+\left(\frac45-1,2\right):\frac{2}{15}\)

\(=\left(-8\right)\cdot\frac{-1}{24}+\left(\frac45-\frac65\right)\cdot\frac{15}{2}\)

\(=\frac13+\frac{-2}{5}\cdot\frac{15}{2}=\frac13-3=-\frac83\)

d: \(\left(-\frac25\right)^2+\frac12\cdot\left(4,5-2\right)-255\)

\(=\frac{4}{25}+\frac12\cdot2,5-255\)

=0,16+1,25-255

=-253,59

\(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\\ =\dfrac{28}{15}.0,25.3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right):\dfrac{47}{24}\\ =\dfrac{7}{15}.3+\dfrac{-47}{60}:\dfrac{47}{24}\\ =\dfrac{7}{5}+\dfrac{-2}{5}\\ =\dfrac{5}{5}=1\)