Các câu hỏi tương tự
a, \(\frac{1}{5\cdot6}+\frac{1}{6\cdot7}+\frac{1}{7\cdot8}+....+\frac{1}{24\cdot25}\)
b, \(\frac{2}{1\cdot3}+\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+.....+\frac{2}{99\cdot101}\)
c, \(5\frac{2}{7}\cdot\frac{8}{11}+5\frac{2}{7}\cdot\frac{5}{11}-5\frac{2}{7}\cdot\frac{2}{11}\)
giup minh voi mai nop roi!!!!
b3 tính nhanh nếu có thểa frac{1}{2}+frac{1}{4}+frac{1}{8}+frac{1}{16}+frac{1}{32}b frac{1}{2}cdotfrac{1}{2}+frac{1}{2}cdotfrac{1}{3}+frac{1}{3}cdotfrac{1}{4}+frac{1}{4}cdotfrac{1}{5}+frac{1}{5}cdotfrac{1}{6}c1frac{1}{24}cdot5frac{2}{5}cdot2-3frac{7}{9}cdot2frac{2}{17}d2frac{3}{13}cdotfrac{26}{58}cdot4cdot2frac{15}{24}cdotfrac{8}{21}e left(1-frac{6}{11}right)-frac{5}{11}fleft(frac{15}{7}-frac{2}{3}right)+frac{2}{3}gleft(frac{5}{8}-frac{1}{4}right)+frac{3}{8}hfrac{3}{3cdot5}+frac{3}{5cdot8}+frac{...
Đọc tiếp
b3 tính nhanh nếu có thể
a \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)
b \(\frac{1}{2}\cdot\frac{1}{2}+\frac{1}{2}\cdot\frac{1}{3}+\frac{1}{3}\cdot\frac{1}{4}+\frac{1}{4}\cdot\frac{1}{5}+\frac{1}{5}\cdot\frac{1}{6}\)
c\(1\frac{1}{24}\cdot5\frac{2}{5}\cdot2-3\frac{7}{9}\cdot2\frac{2}{17}\)
d\(2\frac{3}{13}\cdot\frac{26}{58}\cdot4\cdot2\frac{15}{24}\cdot\frac{8}{21}\)
e \(\left(1-\frac{6}{11}\right)-\frac{5}{11}\)
f\(\left(\frac{15}{7}-\frac{2}{3}\right)+\frac{2}{3}\)
g\(\left(\frac{5}{8}-\frac{1}{4}\right)+\frac{3}{8}\)
\(h\frac{3}{3\cdot5}+\frac{3}{5\cdot8}+\frac{3}{8\cdot11}+\frac{3}{11\cdot14}+\frac{3}{14\cdot17}+\frac{3}{17\cdot20}\)
Tính tổng :a) Afrac{5}{2cdot1}+frac{4}{1cdot11}+frac{3}{11cdot14}+frac{1}{14cdot15}+frac{13}{15cdot28}b) Bfrac{-1}{20}+frac{-1}{30}+frac{-1}{42}+frac{-1}{56}+frac{-1}{72}+frac{-1}{90}c) Cfrac{1}{1cdot2cdot3}+frac{1}{2cdot3cdot4}+...+frac{1}{nleft(n+1right)left(n+2right)}d) Dfrac{1}{1cdot2cdot3cdot4}+frac{1}{2cdot3cdot4cdot5}+...+frac{1}{nleft(n+1right)left(n+2right)left(n+3right)}e) Eleft(frac{1}{1cdot2cdot3}+frac{1}{2cdot3cdot4}+...+frac{1}{37cdot38cdot39}right)cdot1482cdot185cdot8
Đọc tiếp
Tính tổng :
a) \(A=\frac{5}{2\cdot1}+\frac{4}{1\cdot11}+\frac{3}{11\cdot14}+\frac{1}{14\cdot15}+\frac{13}{15\cdot28}\)
b) \(B=\frac{-1}{20}+\frac{-1}{30}+\frac{-1}{42}+\frac{-1}{56}+\frac{-1}{72}+\frac{-1}{90}\)
c) \(C=\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+...+\frac{1}{n\left(n+1\right)\left(n+2\right)}\)
d) \(D=\frac{1}{1\cdot2\cdot3\cdot4}+\frac{1}{2\cdot3\cdot4\cdot5}+...+\frac{1}{n\left(n+1\right)\left(n+2\right)\left(n+3\right)}\)
e) \(E=\left(\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+...+\frac{1}{37\cdot38\cdot39}\right)\cdot1482\cdot185\cdot8\)
Rút gọn:
a,\(A=\frac{5\cdot4^{15}\cdot9^9-4\cdot3^{20}\cdot8^9}{5\cdot2^9\cdot6^{19}-7\cdot2^{29}\cdot27^6}\)
b,\(B=\left(1+\frac{1}{1\cdot3}\right)\left(1+\frac{1}{2\cdot4}\right)\left(1+\frac{1}{3\cdot5}\right)...\left(1+\frac{1}{2014\cdot2016}\right)\)
a)left(10frac{2}{9}cdot2frac{3}{5}right)-6frac{2}{9}b)frac{6}{7}+frac{1}{7}cdotfrac{2}{7}+frac{1}{7}cdotfrac{5}{7}c)3cdot136cdot8+4cdot14cdot6-14cdot150d)frac{1}{6}+frac{1}{12}+frac{1}{20}+frac{1}{30}+frac{1}{42}+frac{1}{56}+...+frac{1}{110}e)frac{2}{3cdot5}+frac{2}{5cdot7}+frac{2}{7cdot9}+...+frac{2}{37cdot39}Tính nhanh nha
Đọc tiếp
a)\(\left(10\frac{2}{9}\cdot2\frac{3}{5}\right)-6\frac{2}{9}\)
b)\(\frac{6}{7}+\frac{1}{7}\cdot\frac{2}{7}+\frac{1}{7}\cdot\frac{5}{7}\)
c)\(3\cdot136\cdot8+4\cdot14\cdot6-14\cdot150\)
d)\(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+...+\frac{1}{110}\)
e)\(\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+\frac{2}{7\cdot9}+...+\frac{2}{37\cdot39}\)
Tính nhanh nha
Tính tổng : a) frac{1}{3cdot5cdot7}+frac{1}{5cdot7cdot9}+frac{1}{7cdot9cdot11}+...+frac{1}{2013cdot2015cdot2017} b) left(1-frac{1}{2^2}right)cdotleft(1-frac{1}{3^2}right)cdotleft(1-frac{1}{4^2}right)cdot...cdotleft(1-frac{1}{2017^2}right) c) left(1-frac{1}{1+2}right)cdotleft(1-frac{1}{1+2+3}right)cdot...cdotleft(1-frac{1}{1+2+3+...+2017}right)
Đọc tiếp
Tính tổng :
a) \(\frac{1}{3\cdot5\cdot7}+\frac{1}{5\cdot7\cdot9}+\frac{1}{7\cdot9\cdot11}+...+\frac{1}{2013\cdot2015\cdot2017}\)
b) \(\left(1-\frac{1}{2^2}\right)\cdot\left(1-\frac{1}{3^2}\right)\cdot\left(1-\frac{1}{4^2}\right)\cdot...\cdot\left(1-\frac{1}{2017^2}\right)\)
c) \(\left(1-\frac{1}{1+2}\right)\cdot\left(1-\frac{1}{1+2+3}\right)\cdot...\cdot\left(1-\frac{1}{1+2+3+...+2017}\right)\)
bài 1 tính tổnga) frac{2}{1cdot3}+frac{2}{3cdot5}+frac{2}{5cdot7}+...+frac{2}{99cdot101}b) frac{5}{1cdot3}+frac{5}{3cdot5}+frac{5}{5cdot7}+...+frac{5}{99cdot101}bài 2 chứng tỏ rằng phân số frac{2n+1}{3n+2}là phân số tối giản.bài 3 cho Afrac{n+2}{n-5}(n thuộc z;n khác 5) tìm x để A thuộc zbài 4 tính giá trị biểu thức A10101cdotleft(frac{5}{111111}+frac{5}{222222}-frac{4}{3cdot7cdot11cdot13cdot37}right)
Đọc tiếp
bài 1 tính tổng
a) \(\frac{2}{1\cdot3}+\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+...+\frac{2}{99\cdot101}\)
b) \(\frac{5}{1\cdot3}+\frac{5}{3\cdot5}+\frac{5}{5\cdot7}+...+\frac{5}{99\cdot101}\)
bài 2 chứng tỏ rằng phân số \(\frac{2n+1}{3n+2}\)là phân số tối giản.
bài 3 cho A=\(\frac{n+2}{n-5}\)(n thuộc z;n khác 5) tìm x để A thuộc z
bài 4 tính giá trị biểu thức
A=\(10101\cdot\left(\frac{5}{111111}+\frac{5}{222222}-\frac{4}{3\cdot7\cdot11\cdot13\cdot37}\right)\)
Tính \(21\cdot\left(\frac{4}{1\cdot3}-\frac{8}{3\cdot5}+\frac{12}{5\cdot7}-\frac{16}{7\cdot9}+...+\frac{36}{17\cdot19}-\frac{40}{19\cdot21}\right)\)
bài 1 Tìm x;y thuộc N* niết
\(\frac{x}{5}-\frac{2}{y}=\frac{2}{15}\)
b) D= \(\frac{2}{3\cdot5}+\frac{3}{5\cdot8}+\frac{11}{8\cdot19}+\frac{13}{19\cdot32}+\frac{25}{32\cdot57}+\frac{30}{57\cdot87}\)