SOLUTION: write the equation of the line perpindicular to X+3Y-12=0 and passing through point (-5, -9)

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Question 440193: write the equation of the line perpindicular to X+3Y-12=0 and passing through point (-5, -9)
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
X%2B3Y-12=0.write it in
Y=-%281%2F3%29X%2B4

any two perpendicular lines are negative reciprocals of each other
if you're given the slope of+-1%2F3, you can find the perpendicular slope by this formula:
mp=-1%2Fm is the perpendicular slope

mp=-1%2F%28-1%2F3%29=3........So the perpendicular slope is mp=3
Also since the unknown line goes through (-5,-9), we can find the equation by plugging in this info into the point-slope formula

Point-Slope Formula:

y-y1=m%28x-x1%29+where m is the slope and (x1,y1) is the given point
y-9=3%28x-5%29+
y-9=3x-15+
y=3x-15%2B9+
y=3x-6+
here is the graph:

+graph%28+500%2C500%2C+-10%2C+10%2C+-10%2C+10%2C+-%281%2F3%29x%2B4%2C+3x-6%29+