Question 846038
Given that {{{a}}}, {{{b}}}, {{{c}}} are in H.P.


So {{{1/a}}},{{{1/b}}},{{{1/c}}} are in A.P.


{{{1/b-1/a=1/c-1/b}}}
{{{(a-b)/ab=(b-c)/bc}}}
{{{(a-b)/a=(b-c)/c}}}
{{{a/c=(a-b)/(b-c)}}}


Where from 'd' comes?