(2.1.2 + 1/1.2) + (2.2.3 + 1/2.3) + (2.3.4 + 1/3.4) + (2.4.5 + 1/4.5)+...+(2.9.10 + 9/10) = ?
(2.1.2+1/1.2) + (2.2.3+1/2.3) + (2.3.4+1/3.4) +...+ (2.9.10/9.10) = ?
\(x = {{3} \over 1^2.2^2}+ {{5} \over 2^2.3^2}+...+{{39} \over 19^2.20^2}\)
\({1 \over x} + {1 \over y} + {1 \over xy} = {2 \over 3}\)
Tìm cặp số nguyên x, y
1. \({3\over 2}x\)+\({1\over 6}\)=\(3{1\over 6}\)
2. x +20% x = 3,6
3. 0,5 x -\({2\over 3}x\)=40%
4. (0,5-\({2\over 3}x\)):\({9\over 10}\)=\({-5\over 3}\)
giúp mình với cac bn ơi
Chứng minh rằng\(A = {1 \over 101}+{1\over 102} +{1\over 103}+{1\over 104}+...+{1\over 200}>{7\over 12}\)
1.
\(A = {3 \over 5}.{2017 \over 2016} - {3 \over 5}- {1 \over 2016} + {2 \over 5}\)
\(B = ({12 \over 199}+ {23 \over 200} - {34 \over 201}).({1\over 2} - {1 \over 3}-{1 \over 6})\)
\(C= 2{1 \over 3}+{11 \over 5}: 33-{1 \over 50}.\)(-5)2
\(D = {4^5 . 9^4 - 10 . 6^9 \over 2^10 . 3^8 + 6^8 . 28}\)
E =( -1).(-1)2.(-1)3.(-1)4......(-1)2014
2.
\(A= {5\over2.4} + {5\over4.6} + {5\over6.8} + .....+ {5\over48.50}\)
\(B={1\over3.6} + {1\over6.9} + {1\over9.12} +.....+{1\over30.33}\)
\( {1 \over 210}+{1 \over 240}+{1 \over 272}+{1 \over 306}\)
Bài 1:So sánh
A=10/22017+10/22018 và B=11/22017+92018
Bài 2
\(A = {1 \over 2}.{3\over 4}.{4\over 5}.{5\over 6}.{7\over 8}. ... .{99\over 100}\) và \(x = {2\over 3}.{4\over 5}.{6\over 7}.{8\over 9}. ... .{100\over 101}\)
a,So sánh
b,Chứng minh A<1/16