SOLUTION: the line 3x+ky=-4 is to be perpendicular to the line 3x-y=7. find the value of k

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Question 349533: the line 3x+ky=-4 is to be perpendicular to the line 3x-y=7. find the value of k
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Convert both lines to slope intercept form, y=mx%2Bb.
3x%2Bky=-4+
ky=3x%2B4
y=%283%2Fk%29x%2B4%2Fk
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3x-y=7
y=3x-7
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.
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Perpendicular lines have slopes that are negative reciprocals,
m%5B1%5D%2Am%5B2%5D=-1
Substituting,
%283%2Fk%29%283%29=-1
highlight%28k=-9%29
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graph%28300%2C300%2C-10%2C10%2C-10%2C10%2C3x-7%2C-%281%2F3%29x-4%2F9%29