x1-x2+(x2-x1)/2x1x2怎么到(x1-x2)(1-1/2x1x2) ?
问题描述：
x1-x2+(x2-x1)/2x1x2怎么到(x1-x2)(1-1/2x1x2) ?
说详细点.
答
x1-x2+(x2-x1)/2x1x2=(x1-x2)*1-(x1-x2)*1/2*(x1-x2)(1*2)=(x1-x2)(1-1/2*1*2)