问题
填空题
添括号计算y2-x2+4x-4=y2-______,x2-y2-______=x2-y2-x-y.
答案
y2-x2+4x-4=y2-(x2-4x+4),
x2-y2-x-y=x2-y2-(x+y),
故填(x2-4x+4);(x+y).
添括号计算y2-x2+4x-4=y2-______,x2-y2-______=x2-y2-x-y.
y2-x2+4x-4=y2-(x2-4x+4),
x2-y2-x-y=x2-y2-(x+y),
故填(x2-4x+4);(x+y).