Question

write an equation of the line containing the given point and perpendicular to the given line
(8,-8); 4x+9y=7
The equation of the line is y = ?

Answer 1

9x-4y=c
to determine c plug x=8,y=-8
so 72+32=c=104
so we have 9x-4y=104..
i assume u know that equation of a line perpendicular to ax+by+c=0 is bx-ay+k=0 where c and k are different constants..
so our answer is y=(1/4)(9x-104)

Answer 2

jazi1 do u get tat? :)

Answer 3

jazi1: could you please try and _understand_ how it is done, and not let the others do all these problems, which are merely the same with different numbers!

Answer 4

nowhereman seems like you are the only one complaining

Answer 5

saubhik I got it but I don't understand it

Answer 6

i think nowhereman is right:) but u shud understand what i did...or ask what u didnt get in this process instead of asking similar problems...:)
happy to help... :)

Answer 7

line 1: 4x + 9y = 7

It should help you to rearrange this equation with y on one side in order to resemble the standard y = mx + b format.

It's critical because you need to identify the slope (m) in order to recreate a parallel or perpendicular line.

In our case:
4x + 9y = 7
9y = 7 - 4x
y = 7/9 - (4/9)x
y = (-4/9)x + 7/9

Can you identify which is the slope (m) in this equation?

Answer 8

ok...jazi1
see if we have perpendicular lines we have product of their slopes as -1.
so u can tell that ax+by+c=0 and bx-ay+k=0 are 2 perpendicular lines..i used this idea..do u get this? :)

Answer 9

saubhik got it

Answer 10

so ur given equation is 4x+9y-7=0..so u know that the perpendicular to it has to be of the form 9x-4y+c=0 where we have to determine the constant c..do u get this? :)

Answer 11

For finding c we just plug the given coordinates! thats it..nice and easy! :)

Answer 12

understood jazi1?

Answer 13

-4x+7
y=--------- = -4x/9 +7/9, here slope m= -4/9
9
now at point(8,-8), from y-y1=m(x-x1)
y-(-8)= -4/9 (x-8)
y+8 = -4x/9 +32/9
y= -4x/9 +32/9 - 8
y=-4x/9 - 40/9 EQ of the line at point(8,-8)

Answer 14

Mark I do thank you but the correct ans is 9/4x - 26

Answer 15

ok good try to review the process i might have missed something there..lol just in a hurry lol

Answer 16

did you see it jazi? lol sorry iwas just in a hurry to give it to you lol...

Answer 17

ok i saw it m=9/4
y-y1=m(x-x1)
y-(-8)=9/4(x-8)
y+8 =9x/4 - 72/4
y = 9x/4 -18 -8
y= 9x/4 -26 answer

Answer 18

y= 9x/4 -26 this is the EQ of perpendicular line to it

Answer 19

Ok thanks mark for being so helpful

Answer 20

wc just understand the process of geting the Eq of the line and the EQ of the line Perpendicular to it..good luck Jazil

Answer 21

saubnik did the other way of geting the line perpendicular to it which i think a kind of advance for the beginers but it is very good techniques and good process too

Answer 22

if a^3 = b^3 + c^3 + d^3 , then least value of a is ?