Leta=√2+√3+√6,b=−√2+√3+√6,c=√2−√3+√6,d=−√2−√3+√6.Evaluate (1a+1b+1c+1d)2.
1a+1b+1c+1d=1√2+√3+√6+1−√2+√3+√6+1√2−√3+√6+1−√2−√3+√6=−12+7√2+5√3−√623+12−7√2+5√3−√623+12+5√2−7√3−2√623+−12−5√2+7√3−2√623=−6√623.
Therefore, (1a+1b+1c+1d)2=216529.
+289 
