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# Q: find dy/dx, in terms of x for x=3tan(2y-1) watch

1. This is a C3 stretch and challenge question. How do you do it?

Q: find dy/dx, in terms of x for x=3tan(2y-1)

I know that dx/dy=6sec^2(2y-1) and dy/dx= 1/(6sec^2(2y-1) but I dont know how to get dy/dx in terms of x and not y
2. your going to have to rearrange x=3tan(2y-1) to find y= and then sub it in to your final answer
3. (Original post by Elitist1991)
This is a C3 stretch and challenge question. How do you do it?

Q: find dy/dx, in terms of x for x=3tan(2y-1)

I know that dx/dy=6sec^2(2y-1) and dy/dx= 1/(6sec^2(2y-1) but I dont know how to get dy/dx in terms of x and not y
Use the relationship 1 + tan^2A = sec^2A in what you have for dy/dx
4. Thanks. The key was realising that the identity could be used

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