Tính nhanh
1/5-3/7+5/9-2/11+7/13-9/16-7/13+2/11-5/9+3/7-1/5
\(\dfrac{1}{5}-\dfrac{3}{7}+\dfrac{5}{9}-\dfrac{2}{11}+\dfrac{7}{13}-\dfrac{9}{16}-\dfrac{7}{13}+\dfrac{2}{11}-\dfrac{5}{9}+\dfrac{3}{7}-\dfrac{1}{5}\)
\(=\)\(\left(\dfrac{3}{7}+\dfrac{-3}{7}\right)+\left(\dfrac{1}{5}-\dfrac{1}{5}\right)+\left(\dfrac{5}{9}-\dfrac{5}{9}\right)+\left(\dfrac{-2}{11}+\dfrac{2}{11}\right)+\left(\dfrac{7}{13}-\dfrac{7}{13}\right)+\dfrac{9}{16}\)
\(=0+0+0+0+0+\dfrac{9}{16}\)
\(=\dfrac{9}{16}\)
1) Tính : a) \(\left(\dfrac{-5}{11}\right)\) .\(\dfrac{7}{15}\) . \(\left(\dfrac{11}{-5}\right)\) .(-30) b) \(\left(\dfrac{11}{12}:\dfrac{33}{16}\right)\). \(\dfrac{3}{5}\) c) \(\dfrac{-7}{15}\).\(\dfrac{5}{8}\).\(\dfrac{15}{-7}\). (-16) d) \(\left(-\dfrac{1}{2}\right)\). \(3\dfrac{1}{5}\)+ \(\left(-\dfrac{1}{2}\right)\).\(-2\dfrac{1}{5}\)
Tính nhanh:
\(\left(\dfrac{-3}{7}+\dfrac{4}{11}\right):\dfrac{7}{11}+\left(\dfrac{-4}{7}+\dfrac{7}{11}\right):\dfrac{7}{11}\)
Các bn giúp mk vs nha
\(\dfrac{6^3+3\cdot6^2+3^3}{-13}\)
1.\(\dfrac{-1}{4}-\dfrac{3}{4}:x=\dfrac{-11}{36}\)
2.\(\left(-1\dfrac{1}{5}+x\right):\left(-3\dfrac{3}{5}\right)=\dfrac{-7}{4}+\dfrac{1}{4}:\dfrac{1}{8}\)
a) \(\dfrac{-2}{7}.\dfrac{21}{8}\) b) 0.24.\(\dfrac{-15}{4}\)
c) (-2).\(\left(\dfrac{-7}{12}\right)\) d) \(\left(\dfrac{-3}{25}\right):6\)
Tìm a,b biết
a+b=a*b=a/b
Cho tam giác ABC cân tại A.Gọi M là trung điểm cạnh BC.
a,C/m tam giác ABM=tam giác ACM
b,Từ M vẽ MH vuông góc AB và MK vuông góc AC.C/m BH=CK
C,Từ B vẽ BP vuông góc AC,BP cắt MH tại I.C/m tam giác IBM cân
16.2x.(x-1/7)=0
Tính
(1-\(\dfrac{1}{2}\))(1-\(\dfrac{1}{3}\))(1-\(\dfrac{1}{4}\))-.(1-\(\dfrac{1}{2017}\))
\(\dfrac{\left(0,6\right)^5}{\left(0,2\right)^6}\)
\(\dfrac{2^7.9^3}{6^5.8^2}\)
\(\dfrac{6^3+3.6^2+3^3}{-13}\)
Mọi người giúp mk nhé.Mk đag cần gấp.Dấu . là nhân nhà
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