1/7*2 + 1/7*4 + 1/7*8 + 1/7*16 + 1/7*32 + 1/7*64
来源:百度知道 编辑:UC知道 时间:2024/06/22 10:19:56
帮忙计 分数来的
用简便算法
用简便算法
1/(7*2 )+ 1/(7*4) + 1/(7*8) + 1/(7*16 )+ 1/(7*32) + 1/(7*64 )
=1/7*(1/2+1/4+1/8+1/16+1/32+1/64)
=1/7*【(1/64+1/64+/32+1/16+1/8+1/4+1/2)-1/64】
(其中1/64+1/64=1/32,1/32+1/32=1/16,1/16+1/16=1/8,1/8+1/8=1/4,1/4+1/4=1/2,1/2+1/2=1)
=1/7*(1-1/64)
=1/7*63/64
=9/64
1/7*2 + 1/7*4 + 1/7*8 + 1/7*16 + 1/7*32 + 1/7*64
=1/7*(2+4+8+16+32+64)
=1/7*【(2+2+4+8+16+32+64)-2】
=1/7*(128-2)
=126*1/7
=18
1/7(2^1+2^2+2^3+2^4+2^5+2^6)
=63*2/7=18
18
1+1/3+1/5+1/7+......1/(2n-1)=?
(1/2-1)*(1/3-1)*(1/4-1)*(1/5-1)*(1/6-1)*(1/7-1)*(1/8-1)*(1/9-1)*(1/10-1)
1+1/2+1/3+1/4+1/5+1/6+1/7+1/8+......+1/100 = ?
2/3,1/2,2/5,1/3,2/7 ()?
1/2-1/3=1/2*1/3 2/5-2/7=2/5*2/7
2(x^2+1)/x+1 + 6(x+1)/x^2+1 =7
3,7/4,1,1/2,( )?
1/2+1/3+1/4+1/5+1/6+1/7+.......+1/99+1/100=?
1/2+1/3+1/4+1/5+1/6+1/7+……+1/2000+1/2001
计算1+1/2+(1/3-1)+1/4+1/5+(1/6-1/2)+1/7+1/8+(1/9/1/3)......