Ta có: \(A=\dfrac{3}{4}.\dfrac{3.5}{4^2}.\dfrac{4.6}{5^2}...\dfrac{49.51}{50^2}\)
\(A=\dfrac{3}{4}.\dfrac{3.4...49}{4.5...50}.\dfrac{5.6...51}{4.5...50}\)
\(A=\dfrac{3}{4}.\dfrac{3}{50}.\dfrac{51}{4}\)
\(A=\dfrac{459}{800}\)
Tính \(A=\dfrac{8}{9}.\dfrac{15}{16}.\dfrac{24}{25}.............................\dfrac{2499}{2500}\)
Cho \(C=\dfrac{3}{4}+\dfrac{8}{9}+\dfrac{15}{16}+....................+\dfrac{2499}{2500}\) Chứng minh \(C>48\)
CMR
S=\(\dfrac{3}{4}\)+\(\dfrac{8}{9}\)+\(\dfrac{15}{16}\)+...+\(\dfrac{2499}{2500}\)>48
Chứng minh:
B = \(2+\dfrac{3}{4}+\dfrac{8}{9}+\dfrac{15}{16}+.....+\dfrac{2499}{2500}< \dfrac{1}{2}\)
Mọi người trả lời nhanh trong hôm nay nhé >v< 
Tối 9h30 mình chốt!!!
thực hiện phép tính( hợp lí nếu có thể)
\(\dfrac{-5}{9}+1\dfrac{5}{9}.\left(\dfrac{3}{4}-\dfrac{2}{5}\right):7^2\)
\(1\dfrac{13}{15}.0,75-\left(\dfrac{104}{195}+25\%\right).\dfrac{24}{47}-3\dfrac{12}{13}:3\)
\(1\dfrac{13}{15}.\left(0,5\right)^2.3+\left(\dfrac{8}{15}-1\dfrac{19}{60}\right):1\dfrac{23}{24}\)
tìm x
\(60\%x+0,4x+x:3=2\)
\(-2x-\dfrac{-3}{5}:\left(0,5\right)^2=-1\dfrac{1}{4}\)
\(\left(\dfrac{2}{3}-x\right):\dfrac{3}{4}=\dfrac{1}{5}\)
Tính
\(1\dfrac{13}{15}.0,75-\left(\dfrac{104}{195}+25\%\right).\dfrac{24}{47}-3\dfrac{12}{13}:3\)
Cho A\(=\dfrac{\left(3\dfrac{2}{15}+\dfrac{1}{5}\right):2\dfrac{1}{2}}{\left(5\dfrac{3}{7}-2\dfrac{1}{4}\right):4\dfrac{43}{56}}\)
B\(=\dfrac{1,2:\left(1\dfrac{1}{5}\cdot1\dfrac{1}{4}\right)}{0,32+\dfrac{2}{25}}\)
Chứng tỏ A=B
Tính :
\(6.\dfrac{-5}{18};\dfrac{-13}{24}+\dfrac{-5}{21}.\dfrac{7}{25};\dfrac{-5}{13}-\dfrac{3}{26}.\dfrac{-2}{3};\left(\dfrac{2}{3}+\dfrac{-7}{6}\right).\left(\dfrac{3}{8}+\dfrac{-3}{24}\right)\)
tính theo cách hợp lý
a)\(\dfrac{4}{20}+\dfrac{16}{42}+\dfrac{6}{15}+\dfrac{-3}{5}+\dfrac{2}{21}+\dfrac{-40}{21}+\dfrac{3}{20}\)
B)\(\dfrac{42}{46}+\dfrac{250}{186}+\dfrac{-2121}{2323}+\dfrac{-125125}{143143}\)