

Given, 1/(a + b + x) = 1/a + 1/b + 1/c
=> 1/(a + b + x) = (bc + ca + ab)/abc
=> a + b + x = abc/(bc + ca + ab)
=> x = abc/(bc + ca + ab) - (a + b)
=> x = {abc -(a + b)(bc + ca + ab)}/(bc + ca + ab)
=> x = {abc - (abc + ca2 + a2 b + b2 c + abc + ab2 )}/(bc + ca + ab)
=> x = {abc - abc - ca2 - a2 b - b2 c - abc - ab2 )}/(bc + ca + ab)
=> x = {-ca2 - a2 b - b2 c - abc - ab2 )}/(bc + ca + ab)
=> x = -{ca2 + a2 b + b2 c + abc + ab2 )}/(bc + ca + ab)
