\(2x-\left[3\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{49}-\frac{1}{51}\right)\right]=0\)
\(\left[3\left(1-\frac{1}{51}\right)\right]=2x\)
\(\left[3\times\frac{50}{51}\right]=2x\)
\(\frac{50}{17}=\frac{2x}{1}\Rightarrow50=17\left(2x\right)\)
50=34x
x=\(\frac{25}{17}\)
TÍNH:
M=\(\frac{6}{1.3}\)+\(\frac{6}{3.5}\)+\(\frac{6}{5.7}\)+...,...+\(\frac{6}{49.51}\)
Tính nhanh
\(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56};\)
\(\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+.......+\frac{3}{49.51};\)
\(\frac{3}{1.3}+\frac{3}{3.5}+\frac{3}{5.7}+.......+\frac{3}{49.51};\)
\(\frac{1}{100.101}+\frac{1}{101.102}+\frac{1}{102.103}+......+\frac{1}{2010.2011}\)
A=\(\frac{3}{1.3}+\frac{3}{3.5}+\frac{3}{3.5}\)+....+\(\frac{3}{49.51}\)
Tính B=\(\frac{1.3}{3.5}+\frac{2.4}{5.7}+\frac{3.5}{7.9}+.....+\frac{49.51}{99.101}\)
Tính : A=\(\frac{17}{1.3}+\frac{17}{3.5}+\frac{17}{5.7}+...+\frac{17}{49.51}\)
tính nhanh
\(A=\frac{3}{1.3}+\frac{3}{3.5}+\frac{3}{5.7}+...+\frac{3}{49.51}\)
\(\frac{5}{1.3}+\frac{5}{3.5}+\frac{5}{5.7}+\)......+\(\frac{5}{49.51}\)
Tính nhanh : \(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+.....+\frac{1}{49.51}\)
tính tổng
\(\frac{3}{1.3}+\frac{3}{3.5}+.....+\frac{3}{49.51}\)
