因式分解x^2-xy-1+1/4y^2
问题描述：
因式分解x^2-xy-1+1/4y^2
答
x^2-xy-1+1/4y^2
=x^2-xy+1/4y^2 -1
=(x-1/2y)^2-1
=(x-1/2y +1)(x-1/2y -1)
答
x²-xy+1/4y²-1
=（x-1/2y）²-1
=（x-1/2y+1）（x-1/2y-1）