x²-4xy-1+4y²=
问题描述：
x²-4xy-1+4y²=
7.77²+4.46×7.77+2.23²=
要有过程哈,兄弟们走起～
答
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