x² —（2n+1）/n（n+1）·x+1/n（n+1）=0 求x=?
问题描述：
x² —（2n+1）/n（n+1）·x+1/n（n+1）=0 求x=?
答
(2n+1)/n(n+1)
=[n+(n+1)]/n(n+1)=1/(n+1)+1/n
x² —（2n+1）/n（n+1）·x+1/n（n+1）=0
x²-[1/(n+1)+1/n]x+1/n*1/(n+1)=0
(x-1/n)[x-1/(n+1)]=0
x=1/n x=1/(n+1)