(x-y)²+16(x-y)+( )=( )²求括号里应填什么?

(x-y)²+16(x-y)+( )=( )²
求括号里应填什么?

解
(x-y)²+16(x-y)+()=()²
(x-y)²+2×(x-y)×8+8²
=[(x-y)+8]²
=(x-y+8)²
第一个括号填64
第二个括号填(x-y+8)²

64 x-y+8

64 x-y+8