a : 3/8 + (25% – 2/3) : 5/3
b : 75% + 6/5 × (-1,25) + 7/3
c : ( 0,4 – 5/6 – 2/15 ) : 8/15 -(-1/4)
d : 0,75 × 16/9 – 7/5 : -21/20
a : 3/8 + (25% – 2/3) : 5/3
b : 75% + 6/5 × (-1,25) + 7/3
c : ( 0,4 – 5/6 – 2/15 ) : 8/15 -(-1/4)
d : 0,75 × 16/9 – 7/5 : -21/20
Đáp án:
$a)\dfrac{1}{8}\\
b)
\dfrac{19}{12}\\
c)
\dfrac{-13}{16}\\
d)
\dfrac{8}{3}\\$
Giải thích các bước giải:
$a) \dfrac{3}{8}+\left ( \dfrac{25}{100}-\dfrac{2}{3} \right ):\dfrac{5}{3}\\
=\dfrac{3}{8}+\left ( \dfrac{1}{4}-\dfrac{2}{3} \right ):\dfrac{5}{3}\\
=\dfrac{3}{8}+\left ( \dfrac{3}{12}-\dfrac{8}{12} \right ):\dfrac{5}{3}\\
=\dfrac{3}{8}+\dfrac{-5}{12}.\dfrac{3}{5}\\
=\dfrac{3}{8}+\dfrac{-1}{4}\\
=\dfrac{3}{8}+\dfrac{-2}{8}\\
=\dfrac{1}{8}\\
b)
\dfrac{75}{100}+\dfrac{6}{5}.(-1,25)+\dfrac{7}{3}\\
=\dfrac{3}{4}+\dfrac{6}{5}.\dfrac{-5}{4}+\dfrac{7}{3}\\
=\dfrac{3}{4}+\dfrac{-3}{2}+\dfrac{7}{3}\\
=\dfrac{9}{12}+\dfrac{-18}{12}+\dfrac{28}{12}\\
=\dfrac{19}{12}\\
c)
\left (0,4-\dfrac{5}{6}-\dfrac{2}{15} \right ):\dfrac{8}{15}-\dfrac{-1}{4}\\
=\left (\dfrac{4}{10}-\dfrac{5}{6}-\dfrac{2}{15} \right ).\dfrac{15}{8}-\dfrac{-1}{4}\\
=\left (\dfrac{2}{5}-\dfrac{5}{6}-\dfrac{2}{15} \right ).\dfrac{15}{8}-\dfrac{-1}{4}\\
=\left (\dfrac{12}{30}-\dfrac{25}{30}-\dfrac{4}{30} \right ).\dfrac{15}{8}-\dfrac{-1}{4}\\
=\dfrac{-17}{30}.\dfrac{15}{8}+\dfrac{1}{4}\\
=\dfrac{-17}{16}+\dfrac{1}{4}\\
=\dfrac{-17}{16}+\dfrac{4}{16}\\
=\dfrac{-13}{16}\\
d)
0,75.\dfrac{16}{9}-\dfrac{7}{5}:\dfrac{-21}{20}\\
=\dfrac{3}{4}.\dfrac{16}{9}-\dfrac{7}{5}.\dfrac{-20}{21}\\
=\dfrac{4}{3}-\dfrac{-4}{3}\\
=\dfrac{8}{3}\\$
Đáp án:
Hình.
Giải thích các bước giải: