1+1+1+1+1+1+1+1+1+1+1:0=?
2+2+2+2+2+2+2+2+2+2×2÷1=?
(1+2/1)*(1+2/2)*(1+2/3) *(1+2/4)*(1+2/5)*(1+2/6)*(1+2/7)*(1+2/8)*(1+2/9)*(1+2/11)*(1+2/12)*...............*(1+2/26)*(1+2/27) = ?
A=(1 - 1/1+2) x (1-1/1+2+3) x (1-1/1+2+3) x (1-1/1+2+3)x1-1/1+2+3+4)x ... x (1-1/1+2+3+...+2018)
a,(1/5-1/7):(30%-20%);b,(3-2 và1/2)x(1/2-1/3)
c,1/2x4+1/4x6+...+1/18x20;d,1/1+2+1/1+2+3+...+1/1+2+3+...+2018
h,1/1.6+2/6.11+2/11.16+2/16.21;g,1/1x2x3+1/2x3x4+...+1/18x19x20
1. Q = 1/1+2 + 1/1+2+3 +1/1+2+3+4 + ............. + 1/1+1+3+4+...+10
2. 1/1 +1/3 +1/6 +1/10 + 1/15 + ... +1/x*{x+1} :2
P=1/1+2+1/1+2+3+1/1+2+3+4+1/1+2+3+4+...+1/1+2+3+4+...+2018
a)S = 1 + 1/3 + 1/9 + 1/27 + ..................... + 1/2187
b)S = 1 + 1/2 + 1/4 + 1/8 + ..................... + 1/128 + 1/256
c)A = 1 + 2 + 4 + 8 + ..................... + 4096 + 8192
d)1/1 x2 + 1/ 2 x 3 + 1/ 3 x 4 + ................. + 1/ 2013 x 2014
h)A = 1/1 x3 + 1/ 3 x 5 + 1/ 5 x 7 + ................. + 1/ 2013 x 2015
bai2a)1/ 2 x (1 + 2) + 1/ 2 x (1 + 2 + 3) + ............ + 1/2 x (1 + 2 + 3 + ....... + 9)
ai nhanh tick đúng nha
2/5 nhân 1/7 + 2/7 nhân 2/5
x + 1/2 nhân 1/3 = 3/4
(1-1/2) nhân (1 - 1/3) nhân ( 1 - 1/4) nhân ... nhân (1 - 1/2020) + x =1/2
tính nhanh
A = 1/1+2 +1/1+2+3 +1/1+2+3+4+...+...+...+1/1+2+3+4+...+2009
A = 1+1/2+1/4+1/8+...+1/4096+1/8192