1/x(x+1)(x+2)+1/(x+1)(x+2)(x+3)..........+1/(x+98)(x+99)(x+100)=?

如题所述

1/x(x+1)(x+2)+1/(x+1)(x+2)(x+3)..........+1/(x+98)(x+99)(x+100)
=(1/2){[1/x(x+1) - 1/(x+1)(x+2)] + [1/(x+1)(x+2) - 1/(x+2)(x+3)]+............
+[1/(x+98)(x+99) - 1/(x+99)(x+100)]}
=(1/2){1/x(x+1) - 1/(x+99)(x+100)}
=[(x+99)(x+100) - x(x+1)]/2x(x+1)(x+99)(x+100)
=[198x+9900]/2x(x+1)(x+99)(x+100)
=[99x+4950]/x(x+1)(x+99)(x+100)
=99(x+50)/x(x+1)(x+99)(x+100)
温馨提示:内容为网友见解,仅供参考
第1个回答  2011-02-28
1/x(x+1)(x+2)=1/x(x+2)-1/(x+1)(x+2)=1/2*1/x-1/(x+1)+1/2*1/(x+2)
1/(x+1)(x+2)(x+3)=1/(x+1)(x+3)-1/(x+2)(x+3)=1/2*1/(x+1)-1/(x+2)+1/2*1/(x+3)
1/(x+2)(x+3)(x+4)=1/(x+2)(x+4)-1/(x+3)(x+4)=1/2*1/(x+2)-1/(x+3)+1/2*1/(x+4)
。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。
1/(x+98)(x+99)(x+100)=1/(x+98)(x+100)-1/(x+99)(x+100)=1/2*1/(x+98)-1/(x+99)+1/2*1/(x+100)
左边相加=右边相加
原式=1/2*[1/x-1/(x+1)-1/(x+99)+1/(x+100)]
第2个回答  2011-02-28
1/[(n-2)(n-1)n]
=1/2[1/(n-2)+1/n]-1/(n-1)
n=x+m
1/(x+m-2)(x+m-1)(x+m)
=1/2[1/(x+m-2)+1/(x+m)]-1/(x+m-1)
1/x(x+1)(x+2)+1/(x+1)(x+2)(x+3)..........+1/(x+98)(x+99)(x+100)
=1/2[1/x+1/(x+2)+1/(x+1)+1/(x+3)+1/(x+2)/1/(x+4)......1/(x+98)+1/(x+97)+1/(x+99)+1/(x+98)+1/(x+100)]-1/(x+1)-1/(x+2)-...-1/(x+99)
=1/2*[1/x-1/(x+1)-1/(x+99)+1/(x+100)]
=99(x+50)/[x(x+1)(x+99)(x+100)]
第3个回答  2011-02-28
1/x(x+1)(x+2)+1/(x+1)(x+2)(x+3)..........+1/(x+98)(x+99)(x+100)
=[1/x(x+1)-1/(x+1)(x+2)]/2+[1/(x+1)(x+2)-1/(x+2)(x+3)]/2+...+[1/(x+98)(x+99)-1/(x+99)(x+100)]/2
=[1/x-2/(x+1)+1/(x-2)]/2+[1/(x+1)-2/(x+2)+1/(x+3)]/2+...+[1/(x+98)-2/(x+99)+1/(x+100)]/2
=[1/x-1/(x+1)-1/(x+99)+1/(x+100)]/2
第4个回答  2011-02-28
其实可设:1/x(x+1)(x+2)=a/x+b/(x+1)+c/(x+2),
通过通分,代数式对应的系数相等,得到:
a+b+c=0,3a+2b+c=0,2a=1,
解得:a=1/2,b=-1,c=1/2。
所以1/x(x+1)(x+2)=1/2*[1/x-2/(x+1)+1/(x+2)]。
同理可推:
1/(x+1)(x+2)(x+3)=1/2*[1/(x+1)-2/(x+2)+1/(x+3)],
.....................................................
1/(x+98)(x+99)(x+100)=1/2*[1/(x+98)-2/(x+99)+1/(x+100)],
所以
原式=1/2*{[1/x-2/(x+1)+1/(x+2)]+[1/(x+1)-2/(x+2)+1/(x+3)]+....+[1/(x+98)-2/(x+99)+1/(x+100)]}
=1/2*[1/x-1/(x+1)-1/(x+99)+1/(x+100)]
=99(x+50)/x(x+1)(x+99)(x+100)。

...+ 1\/(x+2)(x+3)+..+1\/(x+9)(x+10)=1\/x+10 等类似分母递增的多分式问...
这一类的都可以将单项写成两项的差的形势,比如1\/n(n+1)=1\/n - 1\/(n+1)所以题目中的这个式子的左边就等于1\/(x+1) - 1\/(x+2) + 1\/(x+2) - 1\/(x+3) + ... +1\/(x+9) -1\/(x+10)=1\/(x+1) - 1\/(x+10)望采纳 ...

解方程1\/x(x+1)+1\/(x+1)(x+2)+...+1\/(x+8)(x+9)=2x+3\/x(x+9)_百度知...
=(1\/x - 1\/x+1) + (1\/x+1 - 1\/x+2) + ... + (1\/x+8 - 1\/x+9)=1\/x - 1\/x+9 =9\/x(x+9) = 2x+3\/x(x+9)所以9 = 2x+3 x=3

请问这个式子等于什么 1\/(1+x)+1\/(1+x)2+1\/(1+x)3+...1\/(1+x)n...
最后的和=(1-1\/(1+x)^n)\/x 其中x不等于0且不等于1,当x等于0时,和就是n了。

设f(x)=x(x+1)(x+2)...(x+100),求f'(0)=? 大哥们这题目怎么解哦.要方...
由题可求,f'(x)=x[(x+1)...(x+100)]'+x'(x+1)...(x+100)令x=0,f'(0)=0*[(x+1)...(x+100)]+1*(0+1)...(0+100)=100!导数是函数的局部性质。一个函数在某一点的导数描述了这个函数在这一点附近的变化率。如果函数的自变量和取值都是实数的话,函数在某一点的导数...

1\/x+1\/(x+1)+1\/(x+2)+...+1\/(x+n)求大神指点如何化简,谢谢
化简没办法,但 如果是求极限,那夹逼法:n\/(x+n)<sn<n\/x

求y=x(x+1)(x+2)...(x+n)的导数详解
x)'=g(x)+xg(x)'再令 h(x)=(x+2)...(x+n) 则 :g(x)=(x+1)h(x),即 g(x)'=(x+1)'h(x)+(x+1)h(x)'=h(x)+(x+1)h(x)'即 y'=g(x)+x(h(x)+(x+1)h(x)')一次类推直至f(x)=(x+n)即可得到最终导数 当x=0时,此时函数的导数即为y=n!

1\/1X2+1\/2X3+1\/3X4+...+1\/99X100 怎么简便计算。。过程..
=1-1\/100 =99\/100 乘法分配律 简便计算中最常用的方法是乘法分配律。乘法分配律指的是ax(b+c)=axb+axc其中a,b,c是任意实数。相反的,axb+axc=ax(b+c)叫做乘法分配律的逆运用(也叫提取公约数),尤其是a与b互为补数时,这种方法更有用。有时用到了加法结合律,比如a+b+c,b和c互为...

分解因式1+x+x(x+1)+x(x+1)2+...+x(x+1)2009的结果
1+x+x(x+1)+x(x+1)2+...+x(x+1)2009 =(x+1)+x(x+1)+x(x+1)2+...+x(x+1)2009 =(x+1)(1+x+2x+...+2009x)=(x+1)[1+x(1+2+...+2009)]=(x+1)[1+x(1500*2009)]=(x+1)(4350000x+1)

计算1\/(x-1)x+1\/x(x+1)+1\/(x+1)(x+2)+1\/(x+2)(x+3)
x+1\/x(x+1)+1\/(x+1)(x+2)+1\/(x+2)(x+3)=[1\/(x-1)-1\/x]+[1\/x-1\/(x+1)]+[1\/(x+1)-1\/(x+2)]+[1\/(x+2)-1\/(x+3)]=1\/(x-1) -1\/x+1\/x-1\/(x+1)+1\/(x+1)-1\/(x+2)+1\/(x+2)-1\/(x+3)=1\/(x-1)-1\/(x+3)=4\/(x-1)(x+3)...

y=x(x+1)(x+2)(x+3)...(x+n)的导数求法,(详细)
x+n)]'所以,(1\/y)*y'=1\/x+1\/(x+1)+1\/(x+2)+1\/(x+3)+---1\/(x+n)所以,y'=y[1\/x+1\/(x+1)+1\/(x+2)+1\/(x+3)+---1\/(x+n)]即:y'=[x(x+1)(x+2)(x+3)---(x+n)][1\/x+1\/(x+1)+1\/(x+2)+1\/(x+3)+---1\/(x+n)]...

相似回答
大家正在搜