x²;-4xy-1+4y²;= 7.77²;+4.46×7.77+2.23²;= 要有過程哈,兄弟們走起~

x²;-4xy-1+4y²;= 7.77²;+4.46×7.77+2.23²;= 要有過程哈,兄弟們走起~

x²;-4xy-1+4y²;
=x²;-4xy+4y²;-1
=(X-2Y)²;-1
=(X-2Y+1)(X-2Y-1)
7.77²;+4.46×7.77+2.23²;
=7.77²;+2×2.23×7.77+2.23²;
=(7.77+2.23)²;
=10²;
=100