Question 326660
{{{(1/d^2-1/c^2)/(1/c-1/d) =((cd)/(cd))((1/d^2-1/c^2)/(1/c-1/d))}}}
{{{(1/d^2-1/c^2)/(1/c-1/d) =(c/d-d/c)/(d-c)}}}

{{{(1/d^2-1/c^2)/(1/c-1/d) =((cd)/(cd))((c/d-d/c)/(d-c))}}}
{{{(1/d^2-1/c^2)/(1/c-1/d) =(c^2-d^2)/(cd(d-c))}}}
{{{(1/d^2-1/c^2)/(1/c-1/d) =((c-d)(c+d))/(cd(d-c))}}}
{{{(1/d^2-1/c^2)/(1/c-1/d) =-((c-d)(c+d))/(cd(c-d))}}}
{{{(1/d^2-1/c^2)/(1/c-1/d) =highlight(-((c+d))/(cd))}}}