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\(\frac{-4}{9}.\frac{7}{15}+\frac{4}{-9}.\frac{8}{15}\)
\(\Rightarrow\frac{-4}{9}.\frac{7}{15}+\frac{-4}{9}.\frac{8}{15}\)
\(\Rightarrow\frac{-4}{9}.\left(\frac{7}{15}+\frac{8}{15}\right)\)
\(\Rightarrow\frac{-4}{9}.\frac{15}{15}\)
\(\Rightarrow\frac{-4}{9}.1\)
\(\Rightarrow\frac{-4}{9}\)
\(\frac{-4}{9}.\frac{7}{15}+\frac{4}{-9}.\frac{8}{15}\)
\(=\frac{-4}{9}.\frac{7}{15}+\frac{-4}{9}.\frac{8}{15}\)
\(=\frac{-4}{9}.\left(\frac{7}{15}+\frac{8}{15}\right)\)
\(=\frac{-4}{9}.\frac{15}{15}\)
\(=\frac{-4}{9}.1\)
\(=\frac{-4}{9}\)
\(\dfrac{5}{-4}.\dfrac{16}{25}+\dfrac{4}{-9}.\dfrac{8}{15}=-\dfrac{4}{5}+\left(-\dfrac{32}{135}\right)=-\dfrac{28}{27}\)
\(\dfrac{5}{-4}.\dfrac{16}{25}+\dfrac{4}{-9}.\dfrac{8}{15}=\dfrac{-4}{5}+\dfrac{-32}{135}=\dfrac{-28}{27}\)
Bài làm
\(\frac{2}{3}.\frac{7}{15}-\frac{2}{3}.\frac{5}{27}\)
\(=\frac{2}{3}.\left(\frac{7}{15}-\frac{5}{27}\right)\)
\(=\frac{2}{3}.\left(\frac{63}{135}-\frac{25}{135}\right)\)
\(=\frac{2}{3}.\frac{38}{135}\)
\(=\frac{76}{405}\)
~ Nếu rút gọn đc rút hộ ~
\(-\frac{4}{9}.\frac{7}{15}+\frac{4}{9}.\frac{5}{27}\)
\(=-\frac{4}{9}.\frac{7}{15}-\left(-\frac{4}{9}\right).\frac{5}{27}\)
\(=-\frac{4}{9}.\left(\frac{7}{15}-\frac{5}{27}\right)\)
\(=-\frac{4}{9}.\left(\frac{63}{135}-\frac{25}{135}\right)\)
\(=-\frac{4}{9}.\frac{38}{135}\)
\(=\frac{152}{1215}\)
~ Rút gọn đc thì rút ~
# Chúc bạn học tốt #
\(\frac{\frac{2}{3}.\frac{7}{15}-\frac{2}{3}.\frac{5}{27}}{\frac{-4}{9}.\frac{7}{15}+\frac{4}{9}.\frac{5}{27}}=\frac{\frac{2}{3}.\left(\frac{7}{15}-\frac{5}{27}\right)}{\frac{4}{9}\left(\frac{-7}{15}+\frac{5}{27}\right)}=\frac{\frac{2}{3}}{\frac{4}{9}}=\frac{2:3}{4:9}=\frac{2.\frac{1}{3}}{4.\frac{1}{9}}=\frac{1.\frac{1}{3}}{2.\frac{1}{9}}=\frac{1}{6}\)
Bài 1
a, A=5/12.6/11+5/12.5/11+7/12
A=5/12x(6/11+5/11)+7/12
A=5/12x1+7/12
A=12/12=1
Giải:
a) \(\left(9\dfrac{4}{9}+5\dfrac{2}{3}\right)-5\dfrac{1}{2}\)
\(=\left(\dfrac{85}{9}+\dfrac{17}{3}\right)-\dfrac{11}{2}\)
\(=\dfrac{136}{9}-\dfrac{11}{2}\)
\(=\dfrac{173}{18}\)
b) \(\dfrac{13}{9}.\dfrac{15}{4}-\dfrac{13}{9}.\dfrac{7}{4}-\dfrac{13}{9}.\dfrac{5}{4}\)
\(=\dfrac{13}{9}.\left(\dfrac{15}{4}-\dfrac{7}{4}-\dfrac{5}{4}\right)\)
\(=\dfrac{13}{9}.\dfrac{3}{4}\)
\(=\dfrac{13}{12}\)
c) \(\dfrac{2}{3}+\dfrac{5}{8}-\dfrac{-1}{3}+0,375\)
\(=\left(\dfrac{2}{3}-\dfrac{-1}{3}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=1+1\)
\(=2\)
d) \(75\%-3\dfrac{1}{2}+1,5:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{3}{2}:\dfrac{10}{7}\)
\(=\dfrac{3}{4}+\dfrac{7}{2}+\dfrac{21}{20}\)
\(=\dfrac{53}{10}\)
e) \(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\)
\(=\dfrac{28}{15}.\dfrac{1}{4}.3+\left(\dfrac{8}{15}-\dfrac{79}{60}\right):\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-47}{60}:\dfrac{47}{24}\)
\(=\dfrac{7}{5}+\dfrac{-2}{5}\)
\(=1\)
\(\dfrac{-4}{9}.\dfrac{7}{15}+\dfrac{4}{-9}.\dfrac{8}{15}\)
=\(\dfrac{-4}{9}.\left(\dfrac{7}{15}+\dfrac{8}{15}\right)\)
=\(\dfrac{-4}{9}.1\)=\(\dfrac{-4}{9}\)
\(\dfrac{-4}{9}.\dfrac{7}{15}+\dfrac{4}{-9}.\dfrac{8}{15}\)
\(=\dfrac{-4}{9}.\dfrac{7}{15}+\dfrac{-4}{9}.\dfrac{8}{15}\)
\(=\dfrac{-4}{9}.\left(\dfrac{7}{15}+\dfrac{8}{15}\right)\)
\(=\dfrac{-4}{9}.1\)
\(=\dfrac{-4}{9}\)