Question 908854
Let {{{x=1}}} and {{{y=2}}}.
{{{x+y=3}}}
{{{(x+y)^2=9}}}
{{{(x+y)^(-2)=1/9}}}
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{{{x^2=1}}}
{{{x^(-2)=1}}}
{{{y^2=4}}}
{{{y^(-2)=1/4}}}
{{{x^(-2)+y(-2)=1+1/4}}}
{{{x^(-2)+y(-2)=5/4}}}
So clearly,
{{{(x+y)^(-2)<>x^(-2)+y^(-2)}}}