Perpendicular lines have opposite reciprocal slopes, so to find the slope of the line perpendicular to y = 2x -1,
first find the slope of y = 2x - 1, which is 2 (slope is the coefficient of the variable x).
Now we must find the opposite reciprocal of 2, so flip 2 (2/1) over and add a negative sign.
2 becomes -1/2, so your answer is:
A) -1/2
