So sánh 2 biểu thức A và B
A=124x(\(\frac{1}{1\cdot1985}\)+\(\frac{1}{2\cdot1986}\)+\(\frac{1}{3\cdot1987}\)+.....+\(\frac{1}{16\cdot2000}\))
B=\(\frac{1}{1\cdot17}\)+\(\frac{1}{2\cdot18}\)+\(\frac{1}{3\cdot19}\)+......+\(\frac{1}{1984\cdot2000}\)
Tính nhanh:\(\frac{1984\cdot1985+1986\cdot20+1985}{1985\cdot2000-1984\cdot1985}\)
tính nhanh giúp mình nhé
\(\frac{1984\cdot1985+1986\cdot20+1965}{1985\cdot2000-1984\cdot1985}\)
Bạn nào làm nhanh nhất mà đúng mình tích liền
So sánh :
a)\(\frac{3}{124},\frac{1}{41},\frac{5}{207},\frac{2}{83}\)
b)\(\frac{-2525}{2929}và\frac{-217}{245}\)
c)\(A=\frac{3^{10}+1}{3^9+1}vàB=\frac{3^9+1}{3^8+1}\)
d)\(\frac{27}{82}và\frac{26}{75}\)
So sánh:
C = \(100-\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{100}\right)\)và D = \(\frac{1}{2}+\frac{2}{3}+\frac{3}{4}+...+\frac{99}{100}\)
1. tính A= \(\frac{3}{2^2}.\frac{8}{3^2}.\frac{15}{4^2}...\frac{899}{30^2}\)
2. tính B= \(\frac{1}{4}.\frac{2}{6}.\frac{3}{8}.\frac{4}{10}...\frac{30}{62}.\frac{31}{64}\)
3. So sánh C= \(\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{20}\right)\)với \(\frac{1}{21}\)
4. So sánh D= \(\left(1-\frac{1}{4}\right).\left(1-\frac{1}{9}\right).\left(1-\frac{1}{16}\right)...\left(1-\frac{1}{100}\right)\)với \(\frac{11}{19}\)
Bài 1: cho \(\frac{a}{b}<\frac{c}{d}\)(b,d thuộc N sao). Chứng minh \(\frac{a}{b}<\frac{a+c}{b+d}<\frac{c}{d}\)
Bài 2: So sánh A và B biết:
a) \(A=\frac{2^{10}+1}{2^{11}+1};B=\frac{2^{11}+1}{2^{12}+1}\)
b)\(A=\frac{3^{20}+2}{3^{21}+2};B=\frac{3^{21}+2}{3^{22}+2}\)
c)\(A=\frac{7^{15}-4}{7^{16}-4};B=\frac{7^{16}-4}{7^{17}-4}\)
BT1: Cho C=\(\frac{1}{3}\)+\(\frac{1}{5}\)+\(\frac{1}{9}\)+\(\frac{1}{17}\)+\(\frac{1}{33}\)+\(\frac{1}{65}\)
Hãy so sánh C với 1
D=\(\frac{1}{5^2}\)-\(\frac{2}{5^3}\)+\(\frac{3}{5^4}\)-\(\frac{4}{5^5}\)+......+\(\frac{99}{5^{100}}\)-\(\frac{100}{5^{101}}\)
Hãy so sánh D với \(\frac{1}{16}\)
a,\(\frac{2}{3}\cdot\left(\frac{1}{3}+\frac{2}{5}\right)\)
b,24+25+26+.....+99+100
c,\(\frac{16\cdot17-5}{16\cdot16+11}\)
d,\(\frac{5}{80}+\frac{5}{90}+\frac{5}{150}+\frac{5}{210}+\frac{5}{270}\)