Partial differentiation help!!! Watch

bio_ray18
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Question B10

I've worked out part i and got the following answers:

dw/dx = 4x-y+1

dw/dy = -2y-x-z

dw/dz = 6z-y

I can't do part ii, I'm unable to get the values of a,b and c


Can anyone help?
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rowzee
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You just have to solve the system 4x-y+1=0, -2y-x-z=0, 6z-y=0.
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bio_ray18
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I've tried to do that but I keep getting the wrong answer.
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rnd
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(Original post by bio_ray18)
I've tried to do that but I keep getting the wrong answer.
Post your working?
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bio_ray18
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my final answer is (11/50, -6/50, 1/50)

which when substituted back in gives the wrong solution.
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rnd
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(Original post by bio_ray18)
my final answer is (11/50, -6/50, 1/50)

which when substituted back in gives the wrong solution.
So post your working or just keep trying.
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bio_ray18
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dw/dx= 4x-y+1

dw/dy= -2y-x-z

dw/dz= 6z-y

equating them all to zero:
4x-y+1= 0

-2y-x-z= 0

6z-y=0
y=6z

substituting y into the first 2 equations doesnt give correct answers for x and y.
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ghostwalker
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(Original post by bio_ray18)
6z-y=0
y=-6z
Your second line doesn't follow from the first.
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bio_ray18
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(Original post by ghostwalker)
Your second line doesn't follow from the first.
I've adjusted that, but it still doesn't work.
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ghostwalker
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(Original post by bio_ray18)
I've adjusted that, but it still doesn't work.
That is not a helpful comment. Clarify.
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