tính nhanh :
N=\(\frac{1}{337}+2\frac{1}{291}-\frac{290}{291}.\frac{1}{337}-\frac{2}{291.337}\)
So sánh 2 số hữu tỉ sau:
\(\frac{84}{-83}và-\frac{337}{331}\)
Tính nhanh
\(\frac{\frac{1}{3}-\frac{1}{7}-\frac{1}{13}}{\frac{2}{3}-\frac{2}{7}-\frac{2}{13}}.\frac{\frac{3}{4}-\frac{3}{16}-\frac{3}{64}-\frac{3}{264}}{1-\frac{1}{4}-\frac{1}{16}-\frac{1}{64}}+\frac{5}{8}\)
Tính nhanh\(\frac{3}{(1\cdot 2)^{2}}+\frac{5}{(2\cdot 3)^{2}}+\frac{7}{(3\cdot 5)^{2}}+...+\frac{2n+1}{[n\cdot (n+1)^{2}]}\)
Cảm ơn mọi người nhiều!
Tính nhanh B=\(\frac{\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{205}}{\frac{204}{1}+\frac{203}{2}+\frac{202}{3}+...+\frac{1}{204}}\)
Tính nhanh
\(A=\frac{\frac{1}{2}+\frac{1}{3}+....+\frac{1}{2010}}{\frac{2009}{1}+\frac{2008}{2}+...+\frac{1}{2009}}\)
Tính nhanh:
\(\frac{8}{9}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\)\(\frac{1}{2}\)
Tính nhanh:
\(D=182\left[\frac{1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}}{2+\frac{2}{3}+\frac{2}{9}+\frac{2}{27}}:\frac{4-\frac{4}{7}+\frac{4}{49}-\frac{4}{343}}{1-\frac{1}{7}+\frac{1}{49}-\frac{1}{343}}\right]:\frac{919191}{808080}\)
Tính nhanh \(1-\frac{1}{2}+2-\frac{2}{3}+3-\frac{3}{4}+4-\frac{1}{4}-3-\frac{1}{3}-2-\frac{1}{2}-1=?\)