Tính tổng:
A= 1+2014^1+2014^2+2014^3+...+2014^2014+2014^2015
B = 3-3^2+3^3+3^4+...+3^100
A=2014+[2014:(1+2)]+[2014:(1+2+3)]+[2014:(1+2+3+4)]+...++[2014:(1+2+3+...+2013)]
1/3-2/3^2+3/3^3-4/3^4.......2014/3^2014 >1/5
CMR : 1/3-2/3^2+3/3^3-4/3^4+...-2014/3^2014<1/5
1*2*3*4......2015-1*2*3*4...2014-1*2*3*4......2013*2014^2
1*2*3*4......2015-1*2*3*4...2014-1*2*3*4......2013*2014^2
bai 1) tim x, y
x.y-x+2y=3
bai2 ) cmr
a)1/2-1/4+1/8-1/16+1/32-1/64<1/3
b) 1/3-2/3^2+3/3^3-4/3^4+....+99/3^99-100/3^100<3/16
c)1cho tổng gồm 2014 số hạng : s=1/4+2/4^2+3/4^3+.....2014/4^2014
Tính:
A= 2014 + \(\frac{2014}{1+2}+\frac{2014}{1+2+3}+\frac{2014}{1+2+3+4}+........+\frac{2014}{1+2+3+4+.....+2013}\)
1*2*3*...*2015-1*2*3*4*...*2014-1*2*3*...*2013*2014^2 tính nhanh