Thực hiện phép tính: \(1-\frac{3}{2\times10}-\frac{3}{4\times15}-\frac{3}{6\times20}-\frac{3}{8\times25}-...-\frac{3}{198\times500}\)
\(\frac{3}{8\times11}+\frac{4}{11\times15}+\frac{5}{15\times20}+\frac{6}{20\times26}+\frac{7}{26\times33}+\frac{8}{33\times41}+\frac{9}{41\times50}=\frac{2}{5}-2\times x\)
\(T\text{Í}NH:a,\frac{3}{8\times11}+\frac{3}{11\times14}+\frac{3}{14\times17}+\frac{3}{17\times10}\)
\(b,\frac{6}{13\times19}+\frac{6}{19\times25}+...+\frac{6}{613\times619}\)
Bài 4: Tính nhanh:
a, A =\(\left(\frac{84}{13}\right)^2+\left(\frac{35}{13}\right)^2\)
b, B = \(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}\div\frac{3+\frac{3}{13}+\frac{3}{169}+\frac{3}{91}}{7+\frac{7}{13}+\frac{7}{169}+\frac{7}{91}}\)
c, C =\(\frac{1\times2+2\times4+3\times6+4\times8+5\times10}{3\times4+6\times8+9\times12+12\times16+15\times20}\)
\(\frac{4}{3}\times\left(\frac{1}{5}+\frac{1}{4}\right)+\frac{4}{3}\times\left(\frac{3}{16}-\frac{3}{4}\right)\)
\(\frac{3^7\times5^5}{9^2\times15^2}\) \(\frac{8^4\times12^4}{8^{6\times}6^4}\) \(\frac{7^2\times8^4\times16^2}{32^4\times34^3}\)
MỌI NGƯỜI ƠI GIUP MÌNH VỚI
\(\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}+\frac{1}{6\times7}+\frac{1}{7\times8}+\frac{1}{8\times9}+\frac{1}{9\times10}\)
a) \(5\frac{8}{17}\div x+\frac{-1}{17}\div x+3\frac{1}{17}\div17\frac{1}{3}=\frac{4}{17}\)
b)\(\frac{1}{1\times4}+\frac{1}{4\times7}+\frac{1}{7\times10}+...+\frac{1}{x\times\left(x+3\right)}=\frac{6}{19}\)
C=\(\frac{1\times5\times6+2\times10\times12+24\times8\times10}{1\times3\times5+2\times6\times10+8\times6\times20}\)
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
\(A=\frac{5}{1\times7}+\frac{5}{4\times7}+\frac{5}{7\times10}+......+\frac{5}{101\times104}\)