Question 433306
I begin with a generally true statement, which is

{{{(a-1)^2 + (b+1)^2 >= 0}}}

<==> {{{a^2 -2a + 1 + b^2 + 2b + 1 >= 0}}}
<==> {{{a^2 + b^2 >= 2a - 2b - 2}}}
<==> {{{a^2 + b^2 >= 2(a - b - 1)}}}.

Equality holds only if a = 1 and b = -1. (This is obvious if you look at the first inequality in this proof.)