Tinh nhanh
2*6*13/5*13*6
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\(\dfrac{2}{9}+\dfrac{3}{7}+\dfrac{15}{13}+\dfrac{4}{7}-\dfrac{2}{13}+\dfrac{7}{9}\)
\(=\left(\dfrac{2}{9}+\dfrac{7}{9}\right)+\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{15}{13}-\dfrac{2}{13}\right)\)
\(=\dfrac{9}{9}+\dfrac{7}{7}+\dfrac{13}{13}=1+1+1=3\)
\(\dfrac{-5}{9}\).\(\dfrac{-6}{13}\)+\(\dfrac{-5}{9}\).\(\dfrac{-5}{13}\)-\(\dfrac{5}{9}\)
=\(\dfrac{-5}{9}\).(\(\dfrac{-6}{13}\)+\(\dfrac{-5}{13}\)+1)
=\(\dfrac{-5}{9}\).(\(\dfrac{-11}{13}\)+1)
=\(\dfrac{-5}{9}\).\(\dfrac{2}{13}\)
=\(\dfrac{-10}{117}\)
giống bài mình cần mà ko có ai trả lời nhỉ
mong mọi người vô giúp 2 đứa mình với
B=81.(12.(1-1/7-1/289-1/85)/4.(1-1/7-1/289-1/85:5.(1+1/13+1/169+1/91)/6.(1+1/13+1/169+1/91).158158158/711711711
=81.(12/4:5/6).158.1001001/711.1001001
=81.18/5.158/711
=324/5
\(\frac{17}{19}+\left(\frac{13}{5}-\frac{5}{6}\right)-\left(\frac{1}{6}-\frac{2}{19}\right)=\frac{17}{19}+\frac{13}{5}-\frac{5}{6}-\frac{1}{6}+\frac{2}{19}\)
\(=\frac{13}{5}+\left(\frac{17}{19}+\frac{2}{19}\right)+\left(-\frac{5}{6}-\frac{1}{6}\right)\)
\(=\frac{13}{5}+1-1=\frac{13}{5}\)
Đặt \(A=\frac{13}{3}+\frac{13}{6}+\frac{13}{10}+\frac{13}{15}+\frac{13}{21}+\frac{13}{28}+\frac{13}{36}+\frac{13}{45}+\frac{13}{55}\)
\(A=\frac{26}{6}+\frac{26}{12}+\frac{26}{20}+\frac{26}{30}+\frac{26}{42}+\frac{26}{56}+\frac{26}{72}+\frac{26}{90}+\frac{26}{110}\)
\(A=26\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\right)\)
\(A=26\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}\right)\)
\(A=26\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{10}-\frac{1}{11}\right)\)
\(A=26\left(\frac{1}{2}-\frac{1}{11}\right)\)
\(A=26.\frac{9}{22}\)
\(A=\frac{117}{11}\)
Vậy \(A=\frac{117}{11}\)
Chúc bạn học tốt ~
12168/5=2433.6
2433,6 nhé bạn