Johnny, never forget this: PARALLEL lines have the SAME SLOPE; PERPENDICULAR lines have SLOPES that are NEGATIVE RECIPROCALS of each other (for example, 3 and –1/3).
Our given lines is: y = 2x – 1
That equation is written in slope-intercept form, so you can read off the slope by looking at the number in front of the x-term. The number is 2, which is the coefficient of x and also the SLOPE of the line.
Therefore, the slope of the perpendicular line will be –1/2. So we can start our equation of the perpendicular line with: y = (–1/2)x + b
You only have to figure out what b is and then fill it into the equation, and you'll have your equation for the perpendicular line.
So, the question becomes, How do I find b? I am glad that you asked. You fill in the values of x and y from the point you are given into the equation and the solve for b.
I will set it up and let you finish the problem, since it does you no good to have someone give you the answers if you don't read the explanations and do some of the work yourself.
Point (0,–5)
y = (–1/2)x + b
–5 = (–1/2)(0) + b
