1/2+1/4+1/8+1/16+1/32+1/64+1/128
=(1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/128)-1/128
=(1/2+1/4+1/8+1/16+1/32+1/64+1/64)-1/128
=1-1/128=127/128
每一项后面的分母都是前面的一半,所以可以在原来的式子最后+1/128,可以发现从后往前算,就是2个1/128加起来变成1个1/64,然后2个1/64加起来变成1个1/32,依次类推,最后就是2个1/2加起来变成1。
简便计算中常用的定律
1、加法交换律
两个数相加,交换两个加数的位置,和不变,叫做加法交换律。
定律: a+b=b+a
2、加法结合律
三个数相加,先把前二个数相加,再加第三个数,或者,先把后二个数相加,再加上第一个数,其和不变。这叫做加法结合律。
定律: a+b+c=(a+b)+c=a+(b+c)
3、减法性质
在减法中,被减数、减数同时加上或者减去一个数,差不变。
定律:a-b=(a+c)-(b+c) ab=(a-c)-(b-c)
在减法中,被减数增加多少或者减少多少,减数不变,差随着增加或者减少多少。反之,减数增加多少或者减少多少,被减数不变,差随着减少或者增加多少。
在减法中,被减数减去若干个减数,可以把这些减数先加,差不变。
定律:a –b - c = a - (b + c)
4、乘法交换律
个数相乘,交换两个因数的位置,积不变,叫做乘法的交换律。
定律:a×b = b×a
5、乘法结合律
三个数相乘,先把前两个数相乘,再乘以第三个数,或者,先把后两个数相乘,再和第一个数相乘,积不变。这叫做乘法结合律。
定律:a×b×c = a×(b×c)
6、乘法分配律
两个数的和(或差)与一个数相乘,等于把这两个数分别与这个数相乘,再把两个积相加(或相减)。这叫做乘法分配律。
定律: (a + b) ×c= a×c + b×c (a - b)×c= a×c - b×c
1.1/2+1/4+1/8+1/16+1/32+1/64
=32/64+16/64+8/64+4/64+2/64+1/64
=(32+16+8+4+2+1)/64
=63/64
2.1/2+1/4+1/8+1/16+1/32+1/64
=(1-1/2)+(1/2-1/4)+(1/4-1/8)+(1/8-1/16)+(1/16-1/32)+(1/32-1/64)
=1-1/2+1/2-1/4+1/4-1/8+1/8-1/16+1/16-1/32+1/32-1/64
=1-1/64
=63/64
3.原式=1/2+1/4+1/8+1/16+1/32+1/64+1/64-1/64=1-1/64=63/64
4原式
=(32+16+8+4+2+1)/64
=63/64;
5、令m=1/2+1/4+1/8+1/16+1/32+1/64
两边同时乘2,得:
2m=1+1/2+1/4+1/8+...+1/32
两式相减,得:
m=1-1/64=63/646、作一矩形,(对不起,发不了图)对折得1/2,再对折得1/4,再对折得1/8,再对折得1/16,再对折得1/32,再对折得1/64,和为63/64
7、
这个是一个公比为1/2的等比数列求和
Sn=(a1-an×q)/(1-q)=(1/2-1/64×1/2)/(1-1/2)=63/ 64
8、原式=(1/2+1/4)+1/8+1/16+1/32+1/64
=(3/4+1/8)+1/16+1/32+1/64
=(7/8+1/16)+1/32+1/64
=. . .
=63/64
1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128的简便运算
=(1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/64)-1\/128 =1-1\/128=127\/128 每一项后面的分母都是前面的一半,所以可以在原来的式子最后+1\/128,可以发现从后往前算,就是2个1\/128加起来变成1个1\/64,然后2个1\/64加起来变成1个1\/32,依次类推,最后就是2个1\/2加起来变成1。
1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128 简便运算
一道简便计算题,1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128,你会做么
简便计算1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128
=1-1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128 =1-1\/4+1\/8+1\/16+1\/32+1\/64+1\/128 。。。=1-1\/128 =127\/128
计算1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128怎么简便计算
法一:原式+1\/128=1 所以原式=127\/128 法二:等比数列前n项和公式 1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128 =1\/2+(1\/2)^2+(1\/2)^3+……+(1\/2)^7 =1\/2×[1-(1\/2)^7]\/(1-1\/2)=1-(1\/2)^7 =1-1\/128 =127\/128 ...
计算1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128怎么简便计算
原式:1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128 =(1-1\/2)+(1\/2-1\/4)+(1\/4-1\/8)+(1\/8-1\/16)+(1\/16-1\/32)+(1\/32-1\/64)+(1\/64-1\/128)=1-1\/2+1\/2-1\/4+1\/4-1\/8+1\/8-1\/16+1\/16-1\/32+1\/32-1\/64+1\/64-1\/128 =1-1\/128……互相抵消 =...
计算1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128怎么简便计算
=1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128+1\/128-1\/128 =1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/64-1\/128 =1\/2+1\/4+1\/8+1\/16+1\/32+1\/32-1\/128 =1\/2+1\/4+1\/8+1\/16+1\/16-1\/128 =1\/2+1\/4+1\/8+1\/8-1\/128 =1\/2+1\/4+1\/4-1\/128 =1-1\/128 =127\/128...
1\/2+1\/4+1\/8,加1\/16+1\/32+1\/64简便计算?
1\/2+1\/4+1\/8+1\/16+1\/32+1\/64 =1\/2+1\/4+1\/8+1\/16+1\/32+(1\/64+1\/64)-1\/64 =1\/2+1\/4+1\/8+1\/16+(1\/32+1\/32)-1\/64 =1\/2+1\/4+1\/8+(1\/16+1\/16)-1\/64 =1\/2+1\/4+(1\/8+1\/8)-1\/64 =1\/2+(1\/4+1\/4)-1\/64 =1\/2+1\/2-1\/64 =1-1\/64 =...
...1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128这三个简便运算
=1\/2+(1\/2-1\/4)+(1\/4-1\/8)+(1\/8-1\/16)+(1\/16-1\/32)=1-1\/32 =31\/32 1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128 =1\/2+(1\/2-1\/4)+(1\/4-1\/8)+(1\/8-1\/16)+(1\/16-1\/32)+(1\/32-1\/64)+(1\/64-1\/128)=1-1\/128 =127\/128 ...
1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128[简便]?
=1-1\/128 =127\/128 方法2、1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128 =(1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128)×2 -(1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128)=(1+1\/2+1\/4+1\/8+1\/16+1\/32+1\/64)-(1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128)=1-1\/128 ...
1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128等于多少?一定要简算啊!别太复杂了...
将原式加上 1\/128,再减去 1\/128得 1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/128+1\/128-1\/128 =1\/2+1\/4+1\/8+1\/16+1\/32+1\/64+1\/64-1\/128 =1\/2+1\/4+1\/8+1\/16+1\/32+1\/32-1\/128 =.=1-1\/128 =127\/128