4:
a: \(\dfrac{31}{23}-\left(\dfrac{7}{32}+\dfrac{8}{23}\right)\)
\(=\dfrac{31}{23}-\dfrac{7}{32}-\dfrac{8}{23}\)
\(=1-\dfrac{7}{32}=\dfrac{25}{32}\)
b: \(\left(\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}\right)-\left(\dfrac{79}{67}-\dfrac{28}{41}\right)\)
\(=\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}-\dfrac{79}{67}+\dfrac{28}{41}\)
\(=\dfrac{1}{3}+1-1=\dfrac{1}{3}\)
c: \(\left(-30,75\right)+\left(\dfrac{31}{10}-69,25\right)-\left(-6,9\right)\)
\(=-30,75+3,1-69,25+6,9\)
=10-100
=-90
d: \(\left(-34,5\right)\cdot\dfrac{11}{25}-65,5\cdot\dfrac{11}{25}\)
\(=\dfrac{11}{25}\left(-34,5-65,5\right)\)
\(=\dfrac{11}{25}\cdot\left(-100\right)=-44\)
Bài 1:
a: \(\dfrac{1}{6}-0,4\cdot\dfrac{5}{8}+\dfrac{1}{2}\)
\(=\dfrac{1}{6}-\dfrac{2}{5}\cdot\dfrac{5}{8}+\dfrac{1}{2}\)
\(=\dfrac{1}{6}-\dfrac{1}{4}+\dfrac{1}{2}=\dfrac{2-3+6}{12}=\dfrac{5}{12}\)
b: \(\left(-\dfrac{2}{3}\right)^2+\dfrac{1}{6}-\left(-0,5\right)^3\)
\(=\dfrac{4}{9}+\dfrac{1}{6}+\dfrac{1}{8}\)
\(=\dfrac{32+12+9}{72}=\dfrac{53}{72}\)