如图 设直线y=kx(k

题目

如图 设直线y=kx(k

答案

D.10
因为y1=kx1 y2=kx2 kx^2-5=0 x1x2=-5/k
所以x1y2-3x2y1=kx1x2-3kx1x2
=-2kx1x2
=-2k*(-5/k)
=10