# dx/dy and dy/dx confusion!!Watch

Announcements
#1
Hey I wonder if you can help - I'm having trouble with this question...

I realise that the rule that dy/dx is the reciprocal of dx/dy, but I am only managing to get dx/dy in terms of y's - therefore I can't just flip my final fraction to get dy/dx since it'll all be in terms of y!! My final answer for dx/dy (in terms of y) was:

But how to get into dy/dx!!!???

Thanks
0
3 years ago
#2
(Original post by Funky_Giraffe)
Hey I wonder if you can help - I'm having trouble with this question...

I realise that the rule that dy/dx is the reciprocal of dx/dy, but I am only managing to get dx/dy in terms of y's - therefore I can't just flip my final fraction to get dy/dx since it'll all be in terms of y!! My final answer for dx/dy (in terms of y) was:

But how to get into dy/dx!!!???

Thanks
just use the value of y=1 you don't need dy/dx in terms of x
1
3 years ago
#3
(Original post by Funky_Giraffe)
Hey I wonder if you can help - I'm having trouble with this question...

I realise that the rule that dy/dx is the reciprocal of dx/dy, but I am only managing to get dx/dy in terms of y's - therefore I can't just flip my final fraction to get dy/dx since it'll all be in terms of y!! My final answer for dx/dy (in terms of y) was:

But how to get into dy/dx!!!???

Thanks
If it was me I'd rearrange the original equation
0
#4
(Original post by 09sstinson)
just use the value of y=1 you don't need dy/dx in terms of x
Of course! I'm so dumb lol.... so do I just plug in 1 to the final dx/dy I got below? And then that will tell me the gradient at that point?
0
3 years ago
#5
(Original post by Funky_Giraffe)
Of course! I'm so dumb lol.... so do I just plug in 1 to the final dx/dy I got below? And then that will tell me the gradient at that point?
just filp the fraction that you got for dx/dy to get dy/dx in terms of y. then put in y=1
0
#6
(Original post by 09sstinson)
just filp the fraction that you got for dx/dy to get dy/dx in terms of y. then put in y=1
Great! Thanks very much all!
0
3 years ago
#7
(Original post by Funky_Giraffe)
Great! Thanks very much all!
no problem bro
0
X

new posts
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Keele University
Thu, 27 Jun '19
• Birkbeck, University of London
Thu, 27 Jun '19
• University of Birmingham
Fri, 28 Jun '19

### Poll

Join the discussion

#### What was the hardest A-level paper of 2019?

Edexcel Maths paper 1 (49)
24.62%
Edexcel Maths paper 2 (64)
32.16%
AQA Chemistry Paper 2 (37)
18.59%
Edexcel Maths Paper 3 (17)
8.54%
AQA Physics Paper 3 (32)
16.08%