Các câu hỏi tương tự
Tìm x biết :
a) \(\frac{1}{2013}\times x+1+\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{2012\times2013}=2\)
b)\(2x+\frac{7}{6}+\frac{13}{12}+\frac{21}{20}+\frac{31}{30}+\frac{43}{42}+\frac{57}{56}+\frac{73}{72}+\frac{91}{90}=10\)
Tính nhanh:
a,\(\frac{7}{13}\cdot\frac{7}{15}-\frac{5}{12}\cdot\frac{21}{39}+\frac{49}{91}\cdot\frac{8}{15}\)
b,\(\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right)\cdot\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
A=\(1-\frac{5}{6}+\frac{7}{12}-\frac{9}{20}+\frac{11}{30}-\frac{13}{42}+\frac{15}{56}-\frac{17}{72}+\frac{19}{90}-\frac{21}{110}+\frac{23}{132}-\frac{25}{156}\)\(\frac{25}{156}\)
Giups mình nha !!!
1. Tính nhanh
a, \(\frac{7}{13}.\frac{7}{15}-\frac{5}{12}.\frac{21}{39}+\frac{49}{91}.\frac{8}{15}\)
b, \(\left(\frac{12}{199}+\frac{23}{200}-\frac{34}{201}\right).\left(\frac{1}{2}-\frac{1}{3}-\frac{1}{6}\right)\)
c,\(\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)
Cho A=\(\frac{3}{2}+\frac{13}{12}+\frac{21}{20}+...+\frac{9901}{9900}\)và B=\(\frac{5}{6}+\frac{19}{20}+\frac{41}{42}+...+\frac{10099}{10100}\)Tính A-B
a) \(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}\)
b)Cho \(A=\frac{n+2}{n-5}\left(n\inℤ;n\ne5\right)\). Tìm n để \(A\inℤ\)
c) Tìm \(x\inℕ\), biết:
\(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{x.\left(x+1\right)}=\frac{6}{7}\)
1) tính:
a, (\(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{20}{31}\) ).(\(\frac{-5}{12}+\frac{1}{4}+\frac{1}{6}\) )
b, \(\frac{\frac{7}{12}+\frac{5}{6}-1}{5-\frac{3}{4}+\frac{1}{3}}\)
2)Cho A=\(\frac{10n}{5n-3}\)
a) tìm n để A là số nguyên
b)tìm GTLN của A
Rút Gọn:
a.\(\frac{36}{25}.\frac{85}{84}.\frac{20}{34}\)
b.\(\frac{7}{11}.\frac{-39}{190}.\frac{33}{13}.\frac{76}{21}\)
c.\(-\frac{11}{12}.\frac{4}{35}.\frac{84}{-25}.\frac{5}{6}\)
a) Tìm số tự nhiên n để \(\frac{7}{n+9};\frac{8}{n+10};\frac{9}{n+11};\frac{10}{n+12};\frac{11}{n+13}\)tối giản
b) A = \(\frac{n-1}{n+4}\)tìm n thuộc Z để A tối giản