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7 tháng 5 2021 lúc 15:03
Cho \(C=\dfrac{3}{4}+\dfrac{8}{9}+\dfrac{15}{16}+...+\dfrac{9999}{10000}\) . Chứng minh rằng \(C>98\)
Tim cac so nguyen n sao cho:
A=\(\dfrac{n-3}{n+1}\)la so nguyen C=\(\dfrac{2n+3}{n-1}\)la so nguyen
B=\(\dfrac{2n-3}{n+2}\)la so nguyen D=\(\dfrac{-n+5}{n+2}\)la so nguyen
Các bạn giúp với :Bài 1:a, CMR: A dfrac{3}{1^2.2^2}+dfrac{5}{2^2.3^2}+dfrac{7}{3^2.4^2}+...+dfrac{21}{10^2.11^2} 1b, Cho B dfrac{3}{4}+dfrac{8}{9}+dfrac{15}{16}+dfrac{24}{25}+...+dfrac{2499}{2500}. CMR: B không phải là số nguyên.c, So sánh: C dfrac{2}{2^1}+dfrac{3}{2^2}+dfrac{4}{2^3}+...+dfrac{2021}{2^{2020}} với 3.
Đọc tiếp
Các bạn giúp với :<
Bài 1:
a, CMR: A = \(\dfrac{3}{1^2.2^2}+\dfrac{5}{2^2.3^2}+\dfrac{7}{3^2.4^2}+...+\dfrac{21}{10^2.11^2}< 1\)
b, Cho B = \(\dfrac{3}{4}+\dfrac{8}{9}+\dfrac{15}{16}+\dfrac{24}{25}+...+\dfrac{2499}{2500}.\) CMR: B không phải là số nguyên.
c, So sánh: C = \(\dfrac{2}{2^1}+\dfrac{3}{2^2}+\dfrac{4}{2^3}+...+\dfrac{2021}{2^{2020}}\) với 3.
1. tính
a. dfrac{3}{5}-dfrac{2}{3}+dfrac{16}{15}
b. (dfrac{5}{6}-dfrac{4}{5}):dfrac{7}{30}-dfrac{6}{7}
c. dfrac{4}{11}.dfrac{-2}{9}+dfrac{4}{11}.dfrac{-8}{9}+dfrac{4}{11}.dfrac{1}{9}
d.dfrac{-13}{10}-dfrac{15}{16}:dfrac{-3}{4}+dfrac{21}{25}.dfrac{-15}{28}
Đọc tiếp
1. tính
a. \(\dfrac{3}{5}\)-\(\dfrac{2}{3}\)+\(\dfrac{16}{15}\)
b. (\(\dfrac{5}{6}\)-\(\dfrac{4}{5}\)):\(\dfrac{7}{30}\)-\(\dfrac{6}{7}\)
c. \(\dfrac{4}{11}\).\(\dfrac{-2}{9}\)+\(\dfrac{4}{11}\).\(\dfrac{-8}{9}\)+\(\dfrac{4}{11}\).\(\dfrac{1}{9}\)
d.\(\dfrac{-13}{10}\)-\(\dfrac{15}{16}\):\(\dfrac{-3}{4}\)+\(\dfrac{21}{25}\).\(\dfrac{-15}{28}\)
Tính các tích sau:
a) \(P=\dfrac{3}{4}\cdot\dfrac{8}{9}\cdot\dfrac{15}{16}\cdot...\cdot\dfrac{99}{100}\)
b) \(Q=\left(\dfrac{1}{9}-1\right)\left(\dfrac{2}{9}-1\right)\left(\dfrac{3}{9}-1\right)...\left(\dfrac{19}{9}-1\right)\)
so sanh
M=\(\left(\dfrac{1}{2^2}-1\right).\left(\dfrac{1}{3^2}-1\right).\left(\dfrac{1}{4^2}-1\right)...\left(\dfrac{1}{100^2}-1\right)\)va \(\dfrac{1}{2}\)
B=\(\dfrac{1}{20}+\dfrac{1}{21}+...+\dfrac{1}{200}va\dfrac{9}{10}\)
C=\(\dfrac{10}{17}+\dfrac{8}{15}+\dfrac{11}{16}va2\)
23 tháng 3 2021 lúc 20:17
Tính nhanh:
\(B=\dfrac{-5}{9}+\dfrac{8}{15}+\dfrac{-2}{11}+\dfrac{4}{-9}+\dfrac{7}{15}\)
7 tháng 3 2021 lúc 9:35
Tính
B = \(\left(\dfrac{1}{4}-1\right)+\left(\dfrac{1}{9}-1\right)+\left(\dfrac{1}{16}-1\right)....\left(\dfrac{1}{400}-1\right)\)
tính a, \(\dfrac{5.4^{15}.9^9-4.30^{20}8^9}{5.2^9.6^{19}-7.2^{29}.27^6}\)
b, 1\(\dfrac{1}{30}\):\(\left(24\dfrac{1}{6}-24\dfrac{1}{5}\right)-\dfrac{1\dfrac{1}{2}-\dfrac{3}{4}}{4x-\dfrac{1}{2}}=\left(-1\dfrac{1}{15}\right):\left(8\dfrac{1}{5}-8\dfrac{1}{3}\right)\)