试解方程:2/(x+1)(x+2) + 2/(x+2)(x+3)+ … +2/(x+10)(x+11)=5x/(x+1)(x+11)

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试解方程:2/(x+1)(x+2) + 2/(x+2)(x+3)+ … +2/(x+10)(x+11)=5x/(x+1)(x+11)
试解方程:2/(x+1)(x+2) + 2/(x+2)(x+3)+ … +2/(x+10)(x+11)=5x/(x+1)(x+11)

试解方程:2/(x+1)(x+2) + 2/(x+2)(x+3)+ … +2/(x+10)(x+11)=5x/(x+1)(x+11)
裂项求和
即 2(1/(x+1)-1/(x+2))+2(1/(x+2)-1/(x+3))+...2(1/(x+10)-1/(x+11))
=5x/(x+1)(x+11)
即 2*10=5x
所以 x=4

分别把分母项化成2/(x+1)(x+2) =2{1/(x+1)-1/(x+2)},,这样前面的就都相加消去了,,,后面就是很简单了,,自己做吧

脑袋都想炸了。
计算:1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)+.....+1/(x+2003)(x+2004)
[1/(x+1)-1/(x+2)]+[1/(x+2)-1/(x+3)]+[1/(x+3)-1/(x+4)]+...[1/(x+2003)-1/(x+2004)]
把相邻的抵消
剩下1/(x+1)-1/(x+2004)=2003/(x+1)(x+2004)
呵呵,加油 !不懂的话再问,诚答!