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\(A=\left(4+\frac{1}{5}\right).\frac{19}{8}+\left(2+\frac{5}{8}\right).\frac{21}{5}\) =\(\frac{21}{5}.\frac{19}{8}+\frac{21}{8}.\frac{21}{5}\) =\(\frac{21}{5}.\left(\frac{19}{8}+\frac{21}{8}\right)\) = \(\frac{21}{5}.5\) =21 \(B=\frac{25}{2}.\left(3+\frac{2}{7}\right)-\frac{23}{7}.\left(5+\frac{1}{2}\right)\) =\(\frac{25}{2}.\frac{23}{7}-\frac{23}{7}.\frac{11}{2}\) =\(\frac{23}{7}.\left(\frac{25}{2}-\frac{11}{2}\right)\) =\(\frac{23}{7}.7=23\)
Ta có : \(A=8\frac{2}{7}-\left(3\frac{4}{9}+4\frac{2}{7}\right)\)
\(\Rightarrow A=\frac{58}{7}-\left(\frac{31}{9}+\frac{30}{7}\right)\)
\(\Rightarrow A=\frac{58}{7}-\frac{487}{63}=\frac{5}{9}\)
P/s:Câu B tương tự nhé
Tiếp B của @Phạm Tuấn Đạt
\(B=\left(10\frac{2}{9}+2\frac{3}{5}\right)-6\frac{2}{9}\)
\(\Rightarrow B=\left(\frac{92}{9}+\frac{13}{5}\right)-\frac{56}{9}\)
\(B=\left(\frac{92}{9}-\frac{56}{9}\right)+\frac{13}{5}\)
\(B=\frac{36}{9}+\frac{13}{5}\)
\(B=4+\frac{13}{5}\)
\(B=\frac{20}{5}+\frac{13}{5}=\frac{33}{5}\)
A = (4+\(\frac{1}{5}\)) . \(\frac{18}{19}\)+ (2+\(\frac{8}{5}\)) . \(\frac{21}{5}\)
A= \(\frac{21}{5}\).18/19 + 18/5 . 21/5
A= 21/5 (18/19 + 18/5)
A= 21/5 . 432/95
A= 9288/95
b= 25/2. (3+2/7) - 23/7. (5 + 1/2)
b= 25/2 . 23/7 - 23/7 . 11/2
b= 23/7 (25/2 -11/2)
b=23/7 . 7
b= 23
Ta có:
\(2\frac{1}{5}+\frac{3}{5}x=\frac{3}{4}\Rightarrow\frac{3}{5}x=\frac{3}{4}-2\frac{1}{5}=-\frac{29}{20}\Rightarrow x=-\frac{29}{20}:\frac{3}{5}=-\frac{29}{12}\)
Vậy \(x=-\frac{29}{12}\)
\(\left(2\frac{1}{5}+\frac{3}{5}x\right)=\frac{3}{4}\)
\(2\frac{1}{5}+\frac{3}{5}x=\frac{3}{4}\)
\(\frac{11}{5}+\frac{3}{5}x=\frac{3}{4}\)
\(\frac{3}{5}x=\frac{3}{4}-\frac{11}{5}=-\frac{29}{20}\)
\(x=\frac{-29}{20}:\frac{3}{5}=-\frac{29}{12}\)
B= /0,8 -\(2\frac{4}{5}\)/-(-3).(-4)+ 5:50%
B= /\(\frac{4}{5}\)-\(2\frac{4}{5}\)/- 12+5:\(\frac{50}{100}\)
B=/-2/-12 +5.\(\frac{2}{1}\)
B= 2 -12+10
B=0
vậy B=0