SOLUTION: Which of the following is the equation of a line perpendicular to 9y = 3x + 5 that passes through (-2,3)? y = -3x - 3 3y - 6x = 10 y - 3x = -3 y = -3x

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Question 457603: Which of the following is the equation of a line perpendicular to
9y = 3x + 5 that passes through (-2,3)?
y = -3x - 3
3y - 6x = 10
y - 3x = -3
y = -3x - 6
I really don't understand this.
Found 2 solutions by nerdybill, richwmiller:
Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website!
Which of the following is the equation of a line perpendicular to
9y = 3x + 5 that passes through (-2,3)?
y = -3x - 3
3y - 6x = 10
y - 3x = -3
y = -3x - 6
.
Begin by finding the slope of:
9y = 3x + 5
y = (3/9)x + 5/9
y = (1/3)x + 5/9 (slope-intercept form)
we see that the slope is 1/3
a line perpendicular would have to have a slope that is the negative reciprocal -- which is -3
easiest way to inspect the four given answer looking for a -3 slope
y = -3x - 3 (yes)
3y - 6x = 10 (no)
y - 3x = -3 (no)
y = -3x - 6 (yes)
.
now, you only have to pick from two:
y = -3x - 3
y = -3x - 6
to eliminate one we use the given point:(-2,3)
Only the "top" equation works:
y = -3x - 3
3 = -3(-2) - 3
3 = 6 - 3
3 = 3
.
Answer: y = -3x - 3

Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website!
We have to determine the slope of the line
9y = 3x + 5 which is 1/3
then we have to find the slopes of the potential answers
WE are looking for a slope of -3
y = -3x - 3
y = -3x - 6
both have a slope of -3
Is the point (-2,3) on any of those lines
3=-3*-2-3
3=6-3
3=3
y = -3x - 3
works

SOLUTION: Which of the following is the equation of a line perpendicular to 9y = 3x + 5 that passes through (-2,3)? y = -3x - 3 3y - 6x = 10 y - 3x = -3 y = -3x - 6 I really don't