\(\frac{4}{1.3}+\frac{4}{3.5}+........+\frac{4}{2011.2013}\)
\(=2\left(\frac{2}{1.3}+\frac{2}{3.5}+........+\frac{2}{2011.2013}\right)\)
\(=2.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+........+\frac{1}{2011}-\frac{1}{2013}\right)\)
\(=2\left(1-\frac{1}{2013}\right)\)
\(=2.\frac{2012}{2013}\)
\(=\frac{4024}{2013}\)
Các bạn giúp mk, mk cần gấp!
\(\frac{4}{1\times3}+\frac{4}{3\times5}+\frac{4}{5\times7}+......+\frac{4}{99\times101}\)
\(\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}+\frac{1}{6\times7}+\frac{1}{7\times8}+\frac{1}{8\times9}+\frac{1}{9\times10}\)
a,\(\frac{2^3\times3^4}{2^2\times3^2\times5};\frac{2^4\times5^2\times11^2\times7}{2^3\times5^3\times7^2\times11}\)
b,\(\frac{121\times75\times130\times169}{39\times60\times11\times198}\)
c,\(\frac{1998\times1990+3978}{1992\times1991-3984}\)
Bài trên là bài rút gọn các phân số sau
B = \(\frac{59}{10}:\frac{3}{2}-\left(\frac{7}{3}\times\frac{17}{4}-2\times\frac{4}{3}\right)\div\frac{7}{4}\)
C = \(\frac{1}{1\times2}+\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}+\frac{1}{6\times7}\)
Có thánh nào giỏi toán ko vào đây giúp tớ bài này vs help me huhuhuhuhuhu
Tính nhanh : \(\frac{1}{1\times3\times5}+\frac{1}{3\times5\times7}+\frac{1}{5\times7\times9}+.....+\frac{1}{45\times47\times49}\) Help me . Mình cần gấp , HELP
\(\frac{7}{1\times3}+\frac{7}{3\times5}+\frac{7}{5\times7}+......+\frac{7}{99\times101}\)
A=\(\frac{-3}{5}+\left(\frac{-2}{5}+2\right)\)
\(B=\left(6-2\frac{4}{5}\right)\times3\frac{1}{8}-1\frac{3}{5}=\frac{1}{4}\)
Tính nhanh
\(A=\frac{5}{1\times7}+\frac{5}{4\times7}+\frac{5}{7\times10}+......+\frac{5}{101\times104}\)
tính: \(\frac{1}{1\times3}+\frac{1}{3\times5}+\frac{1}{5\times7}+....+\frac{1}{2009\times2011}\)
chứng tỏ:\(\frac{36}{1\times3\times5}+\frac{36}{3\times5\times7}+.....+\frac{36}{25\times27\times29}\)lớn hơn 3
