Question: a line has a slope of 4. what is the slope of any line perpendicular to this line?
Answer: To find the slope of this line we need to get the line into slope-intercept form (y = mx + b), which means we need to solve for y:. The slope of the line –6x – 9y = 4 is m = –2/3. Therefore, the slope of every line perpendicular to this line would have to be m = 3/2 because (–2/3)(3/2) = –1.