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Ta có: \(\dfrac{3}{4}-\left[\left(-\dfrac{3}{5}\right)-\left(\dfrac{1}{12}+\dfrac{2}{9}\right)-\left(-\dfrac{2}{9}-\dfrac{5}{3}\right)\right]\)
\(=\dfrac{3}{4}-\left(-\dfrac{3}{5}-\dfrac{1}{12}-\dfrac{2}{9}+\dfrac{2}{9}+\dfrac{5}{3}\right)\)
\(=\dfrac{3}{4}+\dfrac{3}{5}+\dfrac{1}{12}-\dfrac{5}{3}\)
\(=\dfrac{45}{60}+\dfrac{36}{60}+\dfrac{5}{60}-\dfrac{100}{60}\)
\(=\dfrac{-14}{60}=\dfrac{-7}{30}\)
\(=\dfrac{3}{4}-\left(-\dfrac{5}{3}-\dfrac{11}{36}\right)=\dfrac{3}{4}+\dfrac{71}{36}=\dfrac{49}{18}\)
\(\frac{6}{5}-\frac{1}{4}+\frac{4}{5}-\frac{3}{4}\)
\(=\left(\frac{6}{5}+\frac{4}{5}\right)-\left(\frac{1}{4}+\frac{3}{4}\right)\)
\(=2-1\)
\(=1\)
\(\frac{7}{9}-\frac{5}{12}+\frac{2}{9}-\frac{7}{12}\)
\(=\left(\frac{7}{9}+\frac{2}{9}\right)-\left(\frac{5}{12}+\frac{7}{12}\right)\)
\(=1-1\)
\(=0\)
các câu sau tương tự
A=1
B=0
C=ÂM 8/15
D=0
E=2
F=3/2
H=2/3
LẦN SAU CHO KHÓ SÍU NHA LỚP 5 CŨNG LÀM ĐC
ta có : (ghi lại đề)
=6+12+18+24+30/3+6+9+12+15
=2*(3/3+6/6+9/9+12/12+15/15)
=2*(1+1+1+1+1)
=2*5=10
chúc main học tốt nhé
1) = \(\frac{3}{5}\)
2) =\(\frac{6}{7}\)
3)\(\frac{9}{13}\)
4)\(\frac{4}{13}\)
a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)
\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)
\(=\dfrac{-1621}{126}\)
b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)
a: =-15/24-18/24+60/24
=27/24=9/8
b: =6/12-9/12-10/12-7/12=-20/12=-5/3
c: =17/2+3/7-5/3=305/42
c: =-3-2/3-10/9-25/3-5/6
=-10-19/9-5/6
=-180/18-38/18-15/18=-233/18
\(\dfrac{3}{4}-\left[\left(-\dfrac{5}{3}\right)-\left(\dfrac{1}{12}+\dfrac{2}{9}\right)\right]\)
\(=\dfrac{3}{4}-\left[\left(-\dfrac{5}{3}\right)-\left(\dfrac{9}{108}+\dfrac{24}{108}\right)\right]\)
\(=\dfrac{3}{4}-\left[\left(-\dfrac{5}{3}\right)-\dfrac{11}{36}\right]\)
\(=\dfrac{3}{4}-\left[-\dfrac{60}{36}-\dfrac{11}{36}\right]\)
\(=\dfrac{3}{4}-\dfrac{-71}{36}\)
\(=\dfrac{27}{36}-\dfrac{-71}{36}\)
\(=\dfrac{49}{18}\)
\(\dfrac{3}{4}-\left[\left(-\dfrac{5}{3}\right)-\left(\dfrac{1}{12}+\dfrac{2}{9}\right)\right]=\dfrac{3}{4}-\left[-\dfrac{5}{3}-\dfrac{1}{12}-\dfrac{2}{9}\right]=\dfrac{3}{4}-\left(-\dfrac{71}{36}\right)=\dfrac{49}{18}\)