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1\(\frac{5}{7}\)X \(\frac{3}{4}\)= \(\frac{9}{7}\)
\(\frac{10}{11}\): 1\(\frac{1}{3}\)= \(\frac{15}{22}\)
Ta đặt :1 = 5/7 x 3/4 = 9/7
=> : 10/11 : 1 X 1/3 = ?
<+> : 15/22 .
cHẮC CHẮN 100%%%
\(\left(x-\frac{1}{2}\right).\frac{5}{2}+\frac{1}{2}=\frac{7}{4}\)
\(\left(x-\frac{1}{2}\right).\frac{5}{2}=\frac{7}{4}-\frac{1}{2}\)
\(\left(x-\frac{1}{2}\right).\frac{5}{2}=\frac{7}{4}-\frac{2}{4}\)
\(\left(x-\frac{1}{2}\right).\frac{5}{2}=\frac{5}{4}\)
\(\left(x-\frac{1}{2}\right)=\frac{5}{4}:\frac{5}{2}\)
\(x-\frac{1}{2}=\frac{1}{2}\)
\(x=\frac{1}{2}+\frac{1}{2}\)
\(x=1\)
2/
a) \(\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+\frac{4}{13\cdot17}+\frac{4}{17\cdot21}\)
\(=\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+....+\frac{1}{17}-\frac{1}{21}\right)\)
\(=1-\frac{1}{21}=\frac{20}{21}\)
b) \(\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot...\cdot\left(1-\frac{1}{2017}\right)\)
\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot..\cdot\frac{2016}{2017}\)
\(=\frac{1}{2017}\)
c) \(A=2000-5-5-5-..-5\)(có 200 số 5)
\(A=2000-\left(5\cdot200\right)\)
\(A=2000-1000\)
\(A=1000\)
a= (\(\frac{2}{5}\)+\(\frac{2}{9}\)+\(\frac{2}{11}\)\(\times\)\(\frac{5}{7}\)\(+\frac{7}{9}\)\(+\frac{7}{11}\)\()\)
(9/2-2xX):11/7=77/20
9/2-2xX=121/20
2xX=-31/20
X=-31/40
k mk nha mk đung đó
\(\left(\frac{9}{2}-2\times x\right):1\frac{4}{7}=\frac{11}{4}\times\frac{7}{5}\)
\(\left(\frac{9}{2}-2\times x\right):\frac{11}{7}=\frac{77}{20}\)
\(\frac{9}{2}-2\times x=\frac{77}{20}\times\frac{11}{7}\)
\(\frac{9}{2}-2\times x=\frac{121}{20}\)
\(2\times x=\frac{9}{2}-\frac{121}{20}\)
\(2x=\frac{-31}{20}\)
\(x=\frac{-31}{20}:2\)
\(x=\frac{-31}{40}\)
giúp mk xem lại đề chút nha! vì lớp 5 chưa học số âm!