Đặt \(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)
\(2A=1+\frac{1}{2}+\frac{1}{2^2}+\frac{1}{2^3}+\frac{1}{2^4}\)
\(2A-A=\left(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\right)-\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\right)\)
\(A=1-\frac{1}{32}\)
\(A=\frac{31}{32}\)
1*2*4+2*4*8+4*8*16+8*16*32/1*3*4+2*6*8+4*12*16+8*24*32
Tính
{ 1/2 + 1/4 + 1/8 + 1/16 } : x = 1/2 + 1/6 + 1/8 + 1/12 + ....+ 1/32
Bài 1 Tính nhanh
a) -3/7 + 5/13 + 3/7
b) -5/21+-2/21+8/24
c) -5/11+(-6/11+2)
d) (-1/32+1/2)+15/32
e)5/17+ -6/13 + 3/4 + 7/-13+12/17
f) 7/23+-18/18+-4/9+16/23+-5/8
g)1/3+-3/4+3/5+-1/36+1/15+-2/9
h)-1/2+1/3+-1/4+-2/8+4/18+4/9
{ 1/2 + 1/4 + 1/8 + 1/16 } : x = 1/2 + 1/6 + 1/12 + .....+1/32
1/4*2/6*3/8*…*14/30*15/32=1/2^2x+1
Chứng minh rằng 1/2 - cho 1/4 + 1/8 - cho 1/16 + 1/32 - 1/6 4 <1/3
tính nhanh:
a)1/2+1/6+1/12+1/20+1/30+1/42
b)1/2+1/4+1/8+1/16+1/32
c)1/2+1/4+1/8+...+1/256
1. tính nhanh:
a. M = 7(62+1) (64+1)(68+1)(616+1)(632+1)
b.N=(72+1)(74+1)(78+1)(716+1)
Tính nhanh
A=1/2+1/6+1/12+1/20+1/30+1/42
B=1/2+1/4+1/8+1/6+1/32+1/64
