gradient of curves and differentiation

I am stuck on part c.



Here is my working:

Your part a) has a typo on the numerator which affects c).

For c) the derivative should be very simple (corrected) ,but think about what the original "curve" looks like with k=4. Try factorising.

Ah, thanks for pointing that out! I corrected it and have factorised but I am still unsure on what to think for the curve for when k=4.


Also, does my part b look right?

For c) it asks for the gradient which should be trivial? For the factorised original equation, just root line 2 and what does the curve correspond to? The third line isnt correct.

For b), the numbers look too large? Your working would benefit from an extra line or two.