Question

设logaC,logbC是方程x2-3x+1=0的两根,求loga/bC的值

Answer 1

log(a/b)[c]

=1/{log(c)[a/b]}

而：

log(c)[a/b]=log(c)[a]－log(c)[b]

. =1/{log(a)[c]}－1/{log(b)[c]}

. =(1/x1)－(1/x2)

则：

log(a/b)[c]=1/[(1/x1)－(1/x2)]=(x1x2)/(x2－x1)