How do you find the equation of a line that is perpendicular to the line y=1/8x+9, containing the point (5, 0)?

Question

anonymous · Answer

A perpendicular line means its slope is reciprocated and negated. The slope of the original line is 1/8, so the slope of the new line is -8, giving you:
$$y = -8x+b$$
To orient the line such that it passes through the point (5, 0), insert those values into the new equation and solve for b:
$$0 = (-8)(5)+b$$
40 = b
Thus the perpendicular line that passes through (5, 0) is:
$$y = -8x + 40$$

anonymous · Answer

If you are still here, I have a question.  The equation I was given already had 9 as the value of b.  So I don't think that we would be solving for b..