直线的斜率公式及应用

y=log(8)x=1/3*log(2)x设直线方程为y=kx,与log(8)x交点(x1,kx1),(x2,kx2)kx1=log(8)x1,kx2=log(8)x2分别过M,N作y轴的平行线与函数y=log(2)x的图像交于P,Q则P,Q横坐标分别为x1,x2纵坐标分别为log(2)x1=3log(8)x1=3kx1,log(2)x2=3log(8)x2=3kx2故P(x1,3kx1),Q(x2,3kx2)过P,Q的直线方程为y=3kx,很明显,也经过原点故O,P,Q三点共线