Differentiation II Watch

JudaicImposter
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How to solve Exercise 8H Question 18? See attached workings. I could not arrive to a solution.
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RDKGames
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(Original post by JudaicImposter)
How to solve Exercise 8H Question 18? See attached workings. I could not arrive to a solution.
Towards the end. Not sure where you got this from (red bit below)

It should be \dfrac{(1-x)(1+x)(x-k)}{(x+1)^4} - \dfrac{x}{(x+1)^2} = 0

Hence (1-x)(x-k) - x(x+1) = 0

Now you want this to have a single solution.

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JudaicImposter
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(Original post by RDKGames)
Towards the end. Not sure where you got this from (red bit below)

It should be \dfrac{(1-x)(1+x)(x-k)}{(x+1)^4} - \dfrac{x}{(x+1)^2} = 0

Hence (1-x)(x-k) - x(x+1) = 0

Now you want this to have a single solution.

How to find what value of k gives the equation a single solution when you don't know what x is? If there is one solution the quadratic terms of x would be eliminated.
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RDKGames
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(Original post by JudaicImposter)
How to find what value of k gives the equation a single solution when you don't know what x is? If there is one solution the quadratic terms of x would be eliminated.
It's a quadratic in x... if we impose a condition that it has a single solution, then have a think what that says about the discriminant.
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