which of the following is the equation of a line perpendicular to the line Y= -3/2x+4 and passes through the point (3,9)

A) -2x-3y=-21
B) -2x+3y=21
C) 2x+3y=21
D) 2x-3y=21

Question

which of the following is the equation of a line perpendicular to the line Y= -3/2x+4 and passes through the point (3,9)

A) -2x-3y=-21
B) -2x+3y=21
C) 2x+3y=21
D) 2x-3y=21

misty1212 · Answer

a) find the slope of $y=-\frac{3}{2}x+4$ 
well you don't really find it, you just say it
do you know it?

misty1212 · Answer

if you do not, then say so and i will tell you

anonymous · Answer

-3/2

misty1212 · Answer

ok good
now the perpendicular line will have the slope that is the "negative reciprocal" 
what is that?

anonymous · Answer

3/2

misty1212 · Answer

you didn't flip it

anonymous · Answer

2/3

misty1212 · Answer

ok good
now the point slope formula gives 
$$y-9=\frac{2}{3}(x-3)$$

anonymous · Answer

so what do i do next? im confused :(

misty1212 · Answer

write it in standard form
first multipy all by 3 to get 
$$3y-27=2(x-3)$$ then expand on the left

misty1212 · Answer

$$3y-27=2x-6$$  then put it all on one side of the equal sign

misty1212 · Answer

$$2x-3y=-21$$ which is not an option so maybe 
$$-2x+3y=21$$

misty1212 · Answer

oh yeah that is a choice