ax+by-ay-bx
问题描述：
ax+by-ay-bx
答
ax+by-ay-bx
=x(a-b)-y(a-b)
=(a-b)(x-y)
ax+by-ay-bx
ax+by-ay-bx
=x(a-b)-y(a-b)
=(a-b)(x-y)