Question: find the slope of the line that is perpendicular to y=4x+5?
Answer: The slope-intercept form is y=mx+b y = m x + b , where m m is the slope and b b is the y-intercept. Using the slope-intercept form, the slope is 4 4 . The equation of a perpendicular line to y=4x+5 y = 4 x + 5 must have a slope that is the negative reciprocal of the original slope.