Question

两条直线l1: mx-4y+2=0与l2: 4x+5y+n=0互相垂直,交于点A(2,p)求n+p-m的值.

Answer 1

直线RQ的方程为 y=k（x-1）,与y^2=4x 联立得 k^2*x^2-(2k^2+ky^2-4y-4k=0,(y1-y2)^2=16(k^2+1)/k^2 k^2x^2-2(k^2+