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Question 269921: -8x+5y=3
Find the equation of line through 18,15 parallel to -8x+5y=3 and perpindicular.
I get the slope is 8/5 parallel and -5/8 perp, please help with the rest of the formula.There answer is (-5/8)x+(105/4) and -(-8/5)x+(-69/5). How are they getting the two answers?
Answer by dabanfield(803)   (Show Source):
You can put this solution on YOUR website! Find the equation of line through 18,15 parallel to -8x+5y=3 and perpindicular.
I get the slope is 8/5 parallel and -5/8 perp, please help with the rest of the formula.There answer is (-5/8)x+(105/4) and -(-8/5)x+(-69/5). How are they getting the two answers?
You have the two slopes right :)
The slope-intercept frm of the paralle line is:
y = (8/5)*x + b
Since the line passes through (18,15) we know when x = 18, y = 15 so:
15 = (8/5)*18 + b
b = 144/5 - 15
b = 144/5 - 75/18
b = 69/5
So the parallel line is: y =(8/5)*x + 69/5
The perpendicular line is:
y = (-5/8)*x + b
15 = (-5/8)*18 + b
b = -90/8 - 15
b = -90/8 - 120/8
b = -210/8
b = -105/4
So the perpendicular line is: y = (-5/8)*x - 105/4
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