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26 tháng 7 2021

\(\left(-\dfrac{1}{2}\right)-\left(-\dfrac{3}{5}\right)+9-\dfrac{1}{9}+\dfrac{1}{71}-\left(-\dfrac{2}{7}\right)+\dfrac{4}{35}-\dfrac{7}{18}\)

\(=\left(-\dfrac{22635}{44730}\right)-\left(-\dfrac{26838}{44730}\right)+\dfrac{402570}{44730}-\dfrac{4970}{44730}+\dfrac{630}{44730}-\left(-\dfrac{12780}{44730}\right)+\dfrac{5112}{44730}-\dfrac{35784}{44730}\)

\(=\left(-\dfrac{22635}{44730}\right)+\dfrac{26838}{44730}+\dfrac{402570}{44730}-\dfrac{4970}{44730}+\dfrac{630}{44730}+\dfrac{12780}{44730}+\dfrac{5112}{44730}-\dfrac{35784}{44730}\)

\(=\dfrac{-22635+26838+402570-4970+630+12780+5512-35784}{44730}\)

\(=\dfrac{384941}{44730}\)

25 tháng 7 2019

Bài 2:

a) \(\frac{2}{3}\) - 4 .(\(\frac{1}{2}\) + \(\frac{3}{4}\)) = \(\frac{2}{3}\) - 4 . \(\frac{5}{4}\)

= \(\frac{2}{3}\) - 5 = \(\frac{-13}{3}\)

b) (\(\frac{-1}{3}\) + \(\frac{5}{6}\)) . 11 - 7 = \(\frac{1}{2}\). 11 - 7

= \(\frac{11}{2}\)- 7 = \(\frac{-3}{2}\)

c) \(\frac{-5}{9}\). \(\frac{3}{11}\)+ (\(\frac{-13}{18}\)) . \(\frac{3}{11}\)= \(\frac{3}{11}\). (\(\frac{-5}{9}\)- \(\frac{13}{18}\))

= \(\frac{3}{11}\). (\(\frac{-23}{18}\))= \(\frac{-23}{66}\)

d) \(\frac{-2}{3}\) . \(\frac{3}{11}\)+ (\(\frac{-16}{9}\)) . \(\frac{3}{11}\)= \(\frac{3}{11}\). (\(\frac{-2}{3}\)- \(\frac{16}{9}\))

= \(\frac{3}{11}\). (\(\frac{-22}{9}\)) = \(\frac{-2}{3}\)

Bài 1:

a) =\(\frac{-1}{2}\)+ \(\frac{3}{5}\)- \(\frac{1}{9}\)+ \(\frac{1}{71}\) + \(\frac{2}{7}\) + \(\frac{4}{35}\)- \(\frac{7}{18}\)

= (\(\frac{-1}{2}\)- \(\frac{1}{9}\)- \(\frac{7}{18}\)) + ( \(\frac{3}{5}\)+ \(\frac{2}{7}\)+ \(\frac{4}{35}\)) + \(\frac{1}{71}\)

= -1 + 1 + \(\frac{1}{71}\)= \(\frac{1}{71}\)

b) = 3 - \(\frac{1}{4}\)+ \(\frac{2}{3}\)- 5 + \(\frac{1}{3}\)+ \(\frac{6}{5}\)- 6 + \(\frac{7}{4}\)- \(\frac{3}{2}\)

= (3 - 5 - 6) + (\(\frac{-1}{4}\)+ \(\frac{7}{4}\)- \(\frac{3}{2}\)) + (\(\frac{2}{3}\)+ \(\frac{1}{3}\)) + \(\frac{6}{5}\)

= -8 + 0 + 1 + \(\frac{6}{5}\)

= \(\frac{-29}{5}\)

8 tháng 9 2016

Các bài toán này bn bấm máy thì sẽ ra nha.

Bài 7 có quy tắc tính trong ngoặc trước, ngoài ngoặc sau.

7b bn nhóm 2/3 +1/18 lại vào một chỗ và để cho chúng dấu ngoặc

tíc mình nha

\(=\dfrac{-1}{2}+\dfrac{3}{5}-\dfrac{1}{9}+\dfrac{1}{71}+\dfrac{2}{7}+\dfrac{4}{35}-\dfrac{7}{18}\)

\(=\left(-\dfrac{1}{2}-\dfrac{1}{9}-\dfrac{7}{18}\right)+\left(\dfrac{3}{5}+\dfrac{2}{7}+\dfrac{4}{35}\right)+\dfrac{1}{71}\)

=1/71