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17 votes
17 votes
Write the equation of a line that is perpendicular to y=3x-2 that passes trough the point (-9,5)

User Dinesh Pundkar
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2.6k points

2 Answers

22 votes
22 votes
y= -1/3x + 2

Important takeaway is that the slopes of two perpendicular lines are always negative reciprocals.
User Amcnabb
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2.3k points
9 votes
9 votes


\huge\boxed{y-5&=-(1)/(3)(x+9)}

First, we'll find the slope of the new line. The first line has a slope of
3. Take the negative reciprocal of this (Flip the numerator and denominator, then multiply by
-1) to get
-(1)/(3) for the new slope.

Then, we'll use the point-slope form to make the new equation, where
m is the slope and
(x_1,y_1) is a point on the line:


\begin{aligned}y-y_1&=m(x-x_1)\\y-5&=-(1)/(3)(x-(-9))\\y-5&=-(1)/(3)(x+9)\end{aligned}

Write the equation of a line that is perpendicular to y=3x-2 that passes trough the-example-1
User Kkuilla
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2.8k points