设α=(x1,x2,...,xn)‘,β=(y1,y2,...,yn),这里用’表示转置,α‘即为α的转置,αα’=(x1,x2,...,xn)’(x1,x2,...,xn)=(x1(x1,x2,...,xn)’,x2(x1,x2,...,xn)’,...,xn(x1,x2,...,xn)’)可知αα’的每一列均为(x1,x2,...,xn)’的倍数,即每一列均可由α线性表示,故有R(αα‘)≤R(α)同理有R(ββ’)≤R(β)