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October 07, 2025, 07:49:20 am

Author Topic: Help with gradient perpendicular question?  (Read 6471 times)  Share 

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jmosh002

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Help with gradient perpendicular question?
« on: February 06, 2012, 09:28:00 pm »
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Hi guys,
This is a question from methods 1/2.

Given that the lines (4x - 3y = 10) and (4x - Ly = M) are perpendicular and intersect at the point (4,2), find the values of L and M.

Could someone please explain this to me as i think i have forgotten?

Phy124

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Re: Help with gradient perpendicular question?
« Reply #1 on: February 06, 2012, 10:07:36 pm »
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Firstly, if 4x - Ly = M has an intersect at (4,2) then:

4(4) - L(2) = M

16 - 2L = M

Secondly if 4x - Ly = M is perpendicular to 4x - 3y = 10, then the gradient of 4x - Ly = M will be the negative reciprocal of 4x - 3y = 10

Rearrange 4x - 3y = 10 to find the gradient:

3y = 4x - 10



The gradient of 4x - 3y = 10 is

Therefore the gradient of 4x - Ly = M will be

Rearrange 4x - Ly = M:

Ly = 4x - M

Now we need to work out what L value will make the gradient of the equation (coefficient of x) =









Sub L back into 16 - 2L = M to find M:









I hope that's right, I'll have a read of it just to make sure ;)
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jmosh002

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Re: Help with gradient perpendicular question?
« Reply #2 on: February 07, 2012, 07:25:21 am »
+1
Firstly, if 4x - Ly = M has an intersect at (4,2) then:

4(4) - L(2) = M

16 - 2L = M

Secondly if 4x - Ly = M is perpendicular to 4x - 3y = 10, then the gradient of 4x - Ly = M will be the negative reciprocal of 4x - 3y = 10

Rearrange 4x - 3y = 10 to find the gradient:

3y = 4x - 10



The gradient of 4x - 3y = 10 is

Therefore the gradient of 4x - Ly = M will be

Rearrange 4x - Ly = M:

Ly = 4x - M

Now we need to work out what L value will make the gradient of the equation (coefficient of x) =









Sub L back into 16 - 2L = M to find M:









I hope that's right, I'll have a read of it just to make sure ;)


Thankyou so much!

butene

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Re: Help with gradient perpendicular question?
« Reply #3 on: February 07, 2012, 08:16:01 pm »
0
n/m
« Last Edit: February 07, 2012, 08:19:51 pm by butene »