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19 tháng 7 2016

kq cua mk la 1

19 tháng 7 2016

10,42 : (21,34 - 1/2) + 2/3 * 0,75

= 10,42 : 20,84 + 0,5

= 0,5 + 0,5

=1

18 tháng 8 2018

10,42 : (21,34 - \(\frac{1}{2}\))+\(\frac{2}{3}\).75%

=10,42 : 20,84 +\(\frac{2}{3}\).75%

=\(\frac{1}{2}\)+\(\frac{2}{3}\).75:100

=\(\frac{1}{2}\)+50:100

=\(\frac{1}{2}\)+\(\frac{1}{2}\)=1

\(=0.75-\dfrac{7}{3}-0.75+9\cdot\left(-\dfrac{1}{9}\right)=-\dfrac{7}{3}-1=-\dfrac{10}{3}\)

26 tháng 7 2024

Swassssđccsxssxxxxx

10 tháng 8 2017

\(\left(\dfrac{-2}{3}\right).0,75+\dfrac{1}{\dfrac{2}{3}}:\left(\dfrac{-4}{9}\right)+\left(\dfrac{-1}{2}\right)\)

\(=\left(\dfrac{-2}{3}\right).\dfrac{3}{4}+\dfrac{5}{3}:\left(\dfrac{-8}{18}\right)+\left(\dfrac{-9}{18}\right)\)

\(=\dfrac{-1}{2}+\dfrac{5}{3}.\dfrac{-18}{8}+\dfrac{-9}{18}\)

\(=\dfrac{-1}{2}+\dfrac{-15}{4}+\dfrac{-9}{18}\)

\(=\dfrac{-72}{144}+\dfrac{-540}{144}+\dfrac{-72}{144}\)

\(=\dfrac{-684}{144}\)

\(=\dfrac{-19}{4}.\)

25 tháng 3 2017

0,75 = \(\dfrac{3}{4}\)

Ta có: \(\dfrac{1}{2^2}\) + \(\dfrac{1}{3^2}\) + ... + \(\dfrac{1}{2000^2}\) < \(\dfrac{1}{2.3}\) + \(\dfrac{1}{3.4}\) + ... +\(\dfrac{1}{2000.2001}\).

<=> \(\dfrac{1}{2^2}\) + \(\dfrac{1}{3^2}\) + ... + \(\dfrac{1}{2000^2}\) < \(\dfrac{1}{2}\) - \(\dfrac{1}{3}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{4}\) + ... + \(\dfrac{1}{2000}\) - \(\dfrac{1}{2001}\).

<=> \(\dfrac{1}{2^2}\) + \(\dfrac{1}{3^2}\) + ... + \(\dfrac{1}{2000^2}\) < \(\dfrac{1}{2}\) - \(\dfrac{1}{2001}\).

\(\dfrac{1}{2}\) < \(\dfrac{3}{4}\) nên \(\dfrac{1}{2}\) - \(\dfrac{1}{2001}\) < \(\dfrac{3}{4}\).

Vậy \(\dfrac{1}{2^2}\) + \(\dfrac{1}{3^2}\) + ... + \(\dfrac{1}{2000^2}\) < \(\dfrac{3}{4}\).

12 tháng 2 2018

\(D=\frac{13}{8}+\frac{1}{8}:\left(0,75-\frac{1}{2}\right)-25\%.\frac{1}{2}\)

\(D=\frac{13}{8}+\frac{1}{8}:\left(\frac{3}{4}-\frac{1}{2}\right)-\frac{1}{4}X\frac{1}{2}\)

\(D=\frac{13}{8}+\frac{1}{8}:\frac{1}{4}-\frac{1}{4}X\frac{1}{2}\)

\(D=\frac{13}{8}+\frac{4}{8}-\frac{1}{8}\)

\(D=\frac{17}{8}-\frac{1}{8}\)

\(D=2\)

12 tháng 2 2018

Dễ thế mà ko bik lm hả bạn

18/3+1/8÷(3/4-1/2)-1/4.1/2

18/3+1/8÷-1/4-1/4.1/2

1/8.-4/1-1/4.1/2

-4/8-1/8

-5/8