Question 1209713
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{{{(2 + sqrt(5))(137) = a + b sqrt(5)}}}
{{{274+137sqrt(5)=a+b*sqrt(5)}}}<br>
{{{a=274}}}; {{{b=137}}}<br>
{{{a^2-5b^2=274^2-5*137^2=(2*137)^2-5*137^2=4*137^2-5*137^2=-(137^2)=-18769}}}<br>