Đáp án:
$1)
a)-1\\
b)\dfrac{-17}{9}\\
c)
\dfrac{-11}{20}\\
d)
25.\dfrac{193}{4}$
Giải thích các bước giải:
$1)
a)\dfrac{-7}{25}.\dfrac{11}{13}-\dfrac{7}{25}.\dfrac{2}{13}-\dfrac{18}{25}\\
=\dfrac{-7}{25}.\left ( \dfrac{11}{13}+\dfrac{2}{13} \right )-\dfrac{18}{25}\\
=\dfrac{-7}{25}.\dfrac{13}{13}-\dfrac{18}{25}\\
=\dfrac{-7-18}{25}\\
=\dfrac{-25}{25}\\
=-1\\
b)\dfrac{-5}{9}+\dfrac{5}{9}:\left ( 1\dfrac{2}{3}-2\dfrac{1}{12}\right )\\
=\dfrac{-5}{9}+\dfrac{5}{9}:\left ( \dfrac{5}{3}-\dfrac{25}{12}\right )\\
=\dfrac{-5}{9}+\dfrac{5}{9}:\left ( \dfrac{20}{12}-\dfrac{25}{12}\right )\\
=\dfrac{-5}{9}+\dfrac{5}{9}:\dfrac{20-25}{12}\\
=\dfrac{-5}{9}+\dfrac{5}{9}.\dfrac{12}{-5}\\
=\dfrac{-5}{9}-\dfrac{12}{9}\\
=\dfrac{-5-12}{9}\\
=\dfrac{-17}{9}\\
c)
\left ( \dfrac{-3}{11} \right ).\left ( \dfrac{3}{2}-\dfrac{2}{5} \right )-25.\dfrac{1}{100}\\
=\left ( \dfrac{-3}{11} \right ).\left ( \dfrac{15}{10}-\dfrac{4}{10} \right )-\dfrac{1}{4}\\
=\dfrac{-3}{11}.\dfrac{11}{10}-\dfrac{1}{4}\\
=\dfrac{-3}{10}-\dfrac{1}{4}\\
=\dfrac{(-3).2}{20}-\dfrac{5}{20}\\
=\dfrac{-6-5}{20}\\
=\dfrac{-11}{20}\\
d)
25.\dfrac{1}{100}.2020^0-\left [\left ( 2,25+3\dfrac{3}{4} \right ).(-2)^3 \right ]\\
=\dfrac{1}{4}-\left [\left ( \dfrac{225}{100}+\dfrac{15}{4} \right ).(-8) \right ]\\
=\dfrac{1}{4}-\left [\left ( \dfrac{9}{4}+\dfrac{15}{4} \right ).(-8) \right ]\\
=\dfrac{1}{4}-\left [ \dfrac{9+15}{4}.(-8) \right ]\\
=\dfrac{1}{4}-24.(-2)\\
=\dfrac{1}{4}+48\\
=\dfrac{1}{4}+\dfrac{48.4}{4}\\
=\dfrac{193}{4}$
