Question 6004
In the equation of a line in the form y=mx+b, the coefficient of x is the slope of the line.  The slope of this line {{{y=-3x }}} is therefore the coefficient of x, which is -3.  A line parallel to this line is going in the same direction, so it also has a slope of m= -3.  


A line that is perpendicular to a given line has a slope that is the NEGATIVE RECIPROCAL of the slope of the given line.  Therefore, the slope of a line perpendicular to {{{y = -3x}}} must have a slope that is the opposite sign AND the reciprocal of m = -3, which is  {{{ m = 1/3}}}.


R^2 at SCC