Đặt A = \(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}\)
2A = \(1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\frac{1}{16}\)
2A - A = \(1-\frac{1}{32}\)
=> A = \(\frac{31}{32}\)
tính nhanh p/s 1+ 5/4 + 5/8 + 5/16 + 5/32 + 5/64
b) 1/3 +1/9 + 1/27 + 1/81 +...........+ 1/59049
c) 3/2 + 3/8 + 3/32 +3/128 + 3/512
d) 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + 1/256 giúp mình với 
B=2*4+2*4*8+4*8*16+8*16*32 / 3*4+2*6*8+4*12*16+8*24*32 các bạn có thể giả bằng 1 số nhân với 1 tổng ko ?
1+1+2+2+4+4+8+8+16+16+32+32+64+64=?
bk nha@ >_0
1/2 + 1/4+1/8+1/16+1/32+1/64
1. tinh nhanh: 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128
2. tim x: ( x + 1/2 ) + ( x +1/4 ) + ( x + 1/8 ) + ( x + 1/16 ) = 1
1/2 +1/4+1/8+1/16+1/32
1/2 + 1/4 + 1/8 + 1/16 + 1/32 = ?
1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64
Tính nhanh
B=1/2+1/4+1/8+1/16+1/32+1/64
