\(1\frac{1}{9}\cdot1\frac{1}{10}\cdot1\frac{1}{11}\cdot...\cdot1\frac{1}{2011}\)
dấu chấm ở giữa kia là dấu nhân
tính:
\(1\frac{1}{38}\cdot1\frac{1}{39}\cdot1\frac{1}{40}\cdot\)...(cho đến)...\(\cdot1\frac{1}{2013}\)
Tìm x trong biểu thức sau
\(\left(3\frac{3}{4}:\frac{1}{4}-2\frac{2}{5}\cdot1\frac{1}{4}\right)-\left(3\frac{1}{2}:2,5-\frac{1}{5}\right)-\frac{1}{5}\cdot x=\frac{51}{5}\)
tính nhanh]
b)\(\frac{1\cdot10+2\cdot19+3\cdot18+4\cdot17+.....+18\cdot3+19\cdot2+20\cdot1}{20\cdot\left(1+2+3+.....+19+20\right)-\left(1\cdot2+2+3+3\cdot4+.....+19\cdot20\right)}\)
a \(x\cdot\frac{1}{2}=\frac{3}{4}\) d \(x\cdot1\frac{1}{4}=3\frac{3}{4}\)
b \(x\cdot1\frac{1}{4}=3\frac{3}{4}\) \(1-\left(5-\frac{4}{9}+x-7\frac{7}{18}\right):15\frac{3}{4}=0\) e \(\frac{5}{7}+\frac{4}{5}:x=\frac{5}{6}\)
tính nhanh và ko quy đồng
a] C = \(\frac{5}{2\cdot1}+\frac{4}{1\cdot11}+\frac{3}{11\cdot2}+\frac{1}{2\cdot15}+\frac{13}{15\cdot4}\)
b] B = \(\frac{6}{3\cdot5}+\frac{6}{5\cdot7}+\frac{6}{7\cdot9}+.....+\frac{6}{97\cdot99}\)
\(\frac{45\cdot16-17}{45\cdot15+28}\) các bạn đề là tính nhanh nhé
Ví dụ: \(\frac{2016\cdot2015-5}{2014\cdot2016+2011}=\frac{2016\cdot\left(2014+1\right)-5}{2014\cdot2016+2011}=\frac{2016\cdot2014+2016\cdot1-5}{2014\cdot2016-2011}=\frac{2016\cdot2014+2011}{2014\cdot2016+2011}=1\)
a) \(x+\frac{7}{15}=1\frac{1}{20}\)
b) \(\left(3\frac{1}{2}-x\right)\cdot1\frac{1}{4}=\frac{15}{16}\)
c) \(1\frac{1}{5}x+\frac{2}{3}x=\frac{56}{125}\)
d)\(x+2\frac{1}{4}x=\frac{15}{8}\)
e)\(60\%x+0,4x+x:3=2\)
GIÚP MÌNH NHOA CÁC BẠN
Tinh nhanh:
\(1\frac{1}{3}\times1\frac{1}{8}\times1\frac{1}{15}\times...\times1\frac{1}{9800}\)
