Tính giá trị biểu thức.
5/12 + 3/4 - 1/3 =
1/4 - 3/7 + 11/14 =
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a/\(1248:12-2,5\times4+6,03.\)
\(=104-10+6,03\)
\(=94+6,03=100,03\)
b/\(\left(\frac{2}{3}+\frac{5}{7}-\frac{1}{3}\right)\times\frac{7}{11}+3\frac{1}{3}.\)
\(=\left(\frac{29}{21}-\frac{1}{3}\right)\times\frac{7}{11}+3\frac{1}{3}\)
\(=\frac{22}{11}\times\frac{7}{11}+3\frac{1}{3}\)
\(=\frac{2}{3}+3\frac{1}{3}\)
\(=\frac{2}{3}+\frac{10}{3}\)
\(=\frac{12}{3}=4\)
\(\dfrac{11}{2}\): \(\dfrac{1}{4}\) \(\times\) \(\dfrac{5}{3}\)
= \(\dfrac{11}{2}\) \(\times\) \(\dfrac{4}{1}\) \(\times\) \(\dfrac{5}{3}\)
= 22 \(\times\) \(\dfrac{5}{3}\)
= \(\dfrac{110}{3}\)
\(\dfrac{5}{2}-\dfrac{1}{4}+\dfrac{5}{3}\)
= \(\dfrac{30}{12}-\dfrac{3}{12}+\dfrac{20}{12}\)
= \(\dfrac{7}{12}\)
\(\dfrac{14}{5}\times\dfrac{2}{3}\)+ 5
= \(\dfrac{28}{15}\) + 5
= \(\dfrac{28}{15}\) + \(\dfrac{75}{15}\)
= \(\dfrac{103}{15}\)
\(A=\dfrac{5}{11}.\dfrac{5}{7}+\dfrac{5}{11}.\dfrac{2}{7}+\dfrac{6}{11}=\dfrac{5}{11}\left(\dfrac{5}{7}+\dfrac{2}{7}\right)+\dfrac{6}{11}=\dfrac{5}{11}.1+\dfrac{6}{11}=\dfrac{5}{11}+\dfrac{6}{11}=\dfrac{11}{11}=1\)
\(B=\dfrac{3}{13}.\dfrac{6}{11}+\dfrac{3}{13}.\dfrac{9}{11}-\dfrac{3}{13}.\dfrac{4}{11}=\dfrac{3}{13}\left(\dfrac{6}{11}+\dfrac{9}{11}-\dfrac{4}{11}\right)=\dfrac{3}{13}.1=\dfrac{3}{13}\)
\(C=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right)\left(\dfrac{3}{6}-\dfrac{2}{6}-\dfrac{1}{6}\right)=\left(\dfrac{12}{16}-\dfrac{31}{22}+\dfrac{14}{91}\right).0=0\)
Câu a :
\(\dfrac{5}{12}+\dfrac{3}{4}+\dfrac{1}{3}\\ =\dfrac{5}{12}+\dfrac{9}{12}+\dfrac{4}{12}=\dfrac{3}{2}\)
câu b :
\(\dfrac{1}{4}+\dfrac{3}{7}+\dfrac{11}{14}\\ =\dfrac{7}{28}+\dfrac{12}{28}+\dfrac{22}{28}=\dfrac{41}{28}\)
câu c :
\(\dfrac{1}{4}+\dfrac{3}{12}+\dfrac{12}{36}\\ =\dfrac{3}{12}+\dfrac{3}{12}+\dfrac{4}{12}\\ =\dfrac{10}{12}=\dfrac{5}{6}\)
Ta có: \(S=\left(5-\frac{2}{3}+\frac{3}{2}\right)-\left(7-\frac{5}{4}-\frac{1}{2}\right)-\left(1-\frac{4}{3}+\frac{2}{5}\right).\)
\(\Rightarrow S=\left(\frac{13}{3}+\frac{3}{2}\right)-\left(\frac{23}{4}-\frac{1}{2}\right)-\left(\frac{-1}{3}+\frac{2}{5}\right)\)
\(\Rightarrow S=\frac{35}{6}-\frac{21}{4}-\frac{1}{15}\)
\(\Rightarrow S=\frac{7}{12}-\frac{1}{15}=\frac{31}{60}\)
Vậy \(S=\frac{31}{60}\)
5/12 + 3/4 - 1/3 = 7/6 - 1/3 = 1/2
1/4 - 3/7 + 11/14 = -5/28 + 11/14 = 17/28
a) \(\frac{5}{12}+\frac{3}{4}-\frac{1}{3}=\frac{5}{12}+\frac{9}{12}-\frac{4}{12}=\frac{5+9-4}{12}=\frac{10}{12}=\frac{5}{6}\)
b) \(\frac{1}{4}-\frac{3}{7}+\frac{11}{14}=\frac{7}{28}-\frac{12}{28}+\frac{22}{28}=\frac{7-12+22}{28}=\frac{17}{28}\)