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A = - \(\dfrac{1}{21}\) - \(\dfrac{1}{28}\)
A =- \(\dfrac{4}{84}\)- \(\dfrac{3}{84}\)
A = -\(\dfrac{7}{84}\)
A = - \(\dfrac{1}{12}\)
B = - \(\dfrac{8}{18}\) - \(\dfrac{15}{27}\)
B = - \(\dfrac{4}{9}\) - \(\dfrac{5}{9}\)
B = -1
C = - \(\dfrac{5}{12}\) + 0,75
C = -\(\dfrac{5}{12}\) + \(\dfrac{3}{4}\)
C = - \(\dfrac{5}{12}\) + \(\dfrac{9}{12}\)
C = \(\dfrac{4}{12}\)
C= \(\dfrac{1}{3}\)
D = 3,5 - { - \(\dfrac{2}{7}\))
D = \(\dfrac{7}{2}\) + \(\dfrac{2}{7}\)
D = \(\dfrac{49}{14}\) + \(\dfrac{4}{14}\)
D = \(\dfrac{53}{14}\)
a) \(\frac{-1}{21}\)\(+\)\(\frac{-1}{28}\)\(=\)\(\frac{-1}{12}\)
b) \(\frac{-8}{18}\)\(-\)\(\frac{15}{27}\)\(=\)\(-1\)
c) \(\frac{-5}{12}\)\(+\)\(0.75\)\(=\)\(\frac{-5}{12}\)\(+\)\(\frac{3}{4}\)\(=\)\(\frac{1}{3}\)
d) \(3.5\)\(-\)\(\left(\frac{-2}{7}\right)\)\(=\)\(\frac{7}{2}\)\(+\)\(\frac{2}{7}\)\(=\)\(\frac{53}{14}\)
a)\(\dfrac{-1}{21}+\dfrac{-1}{28}=\dfrac{-4-3}{84}=\dfrac{-7}{84}=\dfrac{-1}{12}\)
b)\(\dfrac{-8}{18}-\dfrac{15}{27}=\dfrac{-24-30}{54}=\dfrac{-54}{54}=-1\)
c)\(\dfrac{-5}{12}+0,75=\dfrac{-5}{12}+\dfrac{3}{4}=\dfrac{-5+9}{12}=\dfrac{4}{12}=\dfrac{1}{3}\)
d)\(3,5-\left(-\dfrac{2}{7}\right)=\dfrac{7}{2}+\dfrac{2}{7}=\dfrac{49+4}{14}=\dfrac{53}{14}\)
câu 1)
\(\dfrac{-12}{18}+\left(\dfrac{-21}{35}\right)=\dfrac{-19}{15}\)
câu 2)
\(-\dfrac{3}{21}+\dfrac{6}{42}=0\)
câu 3)
\(-\dfrac{18}{24}+\dfrac{15}{21}=-\dfrac{1}{28}\)
câu 4)
\(\dfrac{1}{6}+\dfrac{2}{5}=\dfrac{17}{30}\)
câu 5)
\(\dfrac{3}{5}+\left(-\dfrac{7}{4}\right)=-\dfrac{23}{20}\)
câu 6)
\(\left(-2\right)+\left(\dfrac{-5}{8}\right)=\dfrac{-21}{8}\)
câu 7)
\(\dfrac{1}{-8}+\left(-\dfrac{5}{9}\right)=-\dfrac{49}{72}\)
câu 8)
\(\dfrac{4}{13}+\dfrac{12}{39}=\dfrac{8}{13}\)
câu 9)
\(\dfrac{1}{21}+\dfrac{1}{28}=\dfrac{1}{12}\)
câu 10)
\(-\dfrac{3}{29}+\dfrac{16}{58}=\dfrac{5}{29}\)
câu 11)
\(\dfrac{8}{40}+\left(-\dfrac{36}{45}\right)=-\dfrac{3}{5}\)
câu 12)
\(-\dfrac{8}{18}+\left(-\dfrac{15}{27}\right)=-1\)
câu 13)
\(\dfrac{13}{30}+\left(-\dfrac{1}{5}\right)=\dfrac{7}{30}\)
câu 14)
\(\dfrac{2}{21}+\dfrac{1}{28}=\dfrac{11}{84}\)
câu 15)
\(5+\left(-\dfrac{3}{4}\right)=\dfrac{17}{4}\)
câu 16)
\(\dfrac{18}{24}+\dfrac{45}{-10}=-\dfrac{15}{4}\)
