I am looking for a perpendicular line. I'd appreciate ir if you could tell me if I'm on the right track. I am given y=-5x + 4 and know that a perpendicular line passes through (3,5). I think the slope of this line would be 1/5 so it would go up (rise) 1, so the y point would be 6 and it would go over 5 places so x would be 8. I have to come up with the perpendicular line using slope intercept notation. Am I even close? Thanks!!!

Question

I am looking for a perpendicular line. I'd appreciate ir if you could tell me if I'm on the right track.  I am given y=-5x + 4 and know that a perpendicular line passes through (3,5).  I think the slope of this line would be 1/5 so it would go up (rise) 1, so the y point would be 6 and it would go over 5 places so x would be 8.  I have to come up with the perpendicular line using slope intercept notation.  Am I even close?  Thanks!!!

Reiny · Answer

since you know the slope is 1/5 you know the new equation must be

y = (1/5)x + b, but you also know that (3,5) lies on it, so...
5 = (1/5)(3) + b , multiply by 5
25 = 3 + 5b
22 = 5b
b = 22/5

so the equation in the form asked for is

y = (1/5)x + 22/5

chris · Answer

Great...thanks for the clear explanation!:)