解方程1/x(x+2)+1/(x+2)(x+4)+……+1/(x+8)(x-10)=5/24
问题描述:
解方程1/x(x+2)+1/(x+2)(x+4)+……+1/(x+8)(x-10)=5/24
答
实际上就是把每一项分裂,变成两的分式只差,然后跟后面的分式抵消。具体就是
原式=1/2( 1/x-1/(x+2)+1/(x+2)-1/(x+4)+……+1/(x+8)-1/(x+10))=5/24
所以就有1/x-1/(x+10)=5/12,整理的24=x^2+10x,即x^2+10x-24=0
所以(x-2)(x+12)=0,解得x=2 或x=-12
最后检验知两者都是方程的根
答
题目应是1/x(x+2)+1/(x+2)(x+4)+……+1/(x+8)(x+10)=5/241/2( 1/x-1/(x+2)+1/(x+2)-1/(x+4)+……+1/(x+8)-1/(x+10))=5/241/x-1/(x+10)=5/1212*(x+10-x)=5x(x+10)24=x^2+10xx^2+10x-24=0(x-2)(x+12)=0x=2 或x=-12...