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\(a,\frac{-7}{25}.\frac{11}{13}+\frac{-7}{25}.\frac{2}{13}-\frac{18}{25}\)
\(=\frac{-7}{25}.\left(\frac{11}{13}+\frac{2}{13}\right)-\frac{18}{25}=\frac{-7}{25}-\frac{18}{25}=-1\)
\(b,\frac{5}{7}.\frac{1}{3}-\frac{5}{7}.\frac{1}{4}-\frac{5}{7}.\frac{1}{12}=\frac{5}{7}.\left(\frac{1}{3}-\frac{1}{4}-\frac{1}{12}\right)=\frac{5}{7}.\left(\frac{4}{12}-\frac{3}{12}-\frac{1}{12}\right)\)
\(=\frac{5}{7}.0=0\)
c)\(5\frac{2}{5}.4\frac{2}{7}+5\frac{5}{7}.5\frac{2}{5}=\frac{27}{5}.\frac{30}{7}+\frac{40}{7}.\frac{27}{5}=\frac{27}{5}.\left(\frac{30}{7}+\frac{40}{7}\right)\)
\(=\frac{27}{5}.10=27.2=54\)
\(d,75\%-1\frac{1}{2}+0,5:\frac{5}{12}-\left(\frac{-1}{2}\right)^2=\frac{3}{4}-\frac{3}{2}+\frac{1}{2}.\frac{12}{5}-\frac{1}{4}\)
\(=\left(\frac{3}{4}-\frac{1}{4}\right)-\frac{3}{2}+\frac{6}{5}=\frac{1}{2}-\frac{3}{2}+\frac{6}{5}=-1+\frac{6}{5}=\frac{-5}{5}+\frac{6}{5}=\frac{1}{5}\)
\(A=\frac{1}{3}.\frac{-9}{10}.\frac{-6}{13}.\frac{-13}{36}=\frac{-3}{10}.\frac{-1}{6}=\frac{1}{20}\)
\(B=\frac{4}{19}\left(\frac{-5}{12}+\frac{-7}{12}\right)-\frac{40}{57}=\frac{-4}{19}-\frac{40}{57}=\frac{-52}{57}\)
2 câu còn lại tự làm
\(A=\frac{1}{3}.\frac{-6}{13}.\frac{-9}{10}.\frac{-13}{36}\)
\(A=\frac{1}{1}.\frac{-2}{13}.\frac{-9}{10}.\frac{-13}{36}\)
\(A=\frac{-2}{13}.\frac{-9}{10}.\frac{-13}{36}\)
\(A=\frac{-1}{13}.\frac{-9}{5}.\frac{-13}{36}\)
\(A=\frac{-1}{13}.\frac{-1}{5}.\frac{-13}{4}\)
\(A=\frac{-13}{260}=\frac{-1}{20}\)
Câu a:
-4\(\frac38\) + (39\(\frac38\) - 5\(\frac{7}{32}\))
= -4 - \(\frac38\) + 39 + \(\frac38\) - 5 - \(\frac{7}{32}\)
= (-4 + 39 - 5) + (-3/8 + 3/8 - 7/32)
= (35 - 5) + (0 - 7/32)
= 30 - 7/32
= 953/32
Câu b:
2\(\frac12\) + 19\(\frac{3}{11}\).\(\frac{7}{26}\) -6\(\frac{3}{11}\).\(\frac{7}{26}\)
= 5/2 + 7/26.(19 + 3/11 - 6 - 3/11)
= 5/2 + 7/26.[(19 - 6) + (3/11 - 3/11)
= 5/2 + 7/26.[13 + 0]
= 5/2 + 7/26.13
= 5/2 + 7/2
= 6
\(4\frac{2}{7}.3=\left(4+\frac{2}{7}\right).3=4.3+\frac{2}{7}.3=12+\frac{6}{7}=12\frac{6}{7}\)
Cách này nhanh hơn nhiều đúng không
x.\(2\frac{3}{14}\)+ x.\(3\frac{2}{7}\)= 5 - \(2\frac{3}{4}\)
x.\(\frac{31}{14}\)+ x.\(\frac{23}{7}\)=5 -\(\frac{11}{4}\)
x (\(\frac{31}{14}\)+ \(\frac{23}{7}\) = \(\frac{20}{4}\)- \(\frac{11}{4}\)
x ( \(\frac{31}{14}\)+ \(\frac{46}{14}\))=\(\frac{9}{4}\)
x\(\frac{11}{2}\) =\(\frac{9}{4}\)
x =\(\frac{9}{4}\):\(\frac{11}{2}\)
x =\(\frac{9}{4}\). \(\frac{2}{11}\)
x =\(\frac{9}{2.11}\)
x =\(\frac{9}{22}\)
a, \(\frac{7}{12}\)-\(\frac{27}{7}\)x\(\frac{1}{18}\)=\(\frac{31}{84}\)
câu b đáp án là \(\frac{-2}{15}\)
a
\(5\frac{4}{7}:x+=13\)
\(\frac{39}{7}:x=13\)
\(x=\frac{39}{7}:13\)
\(x=\frac{3}{7}\)
\(\frac{4}{7}x=\frac{9}{8}-0,125\)
\(\frac{4}{7}x=1\)
\(x=1:\frac{4}{7}\)
\(x=\frac{7}{4}=1\frac{3}{4}\)
ta có:
\(4\frac{2}{7}=4+\frac{2}{7}\)
\(4\frac{2}{7}=\left(4+\frac{2}{7}\right)\cdot3=4\cdot3+\frac{2}{7}\cdot3=12+\frac{6}{7}=12\frac{6}{7}\)