# Math Help - General differentiation questions

1. Originally Posted by Apex
Hi

I carried with Q9 but got stuck. See Q9 below.

Thanks alot
Apex
so set the other part equal to zero and solve.

$\sin x + \frac {x \cos x }2 = 0$ has solutions

2. Originally Posted by Apex
This one requires more of an explanation
the derivative went from a negative value to a positive value on a continuous, smooth curve, it means the derivative had to hit zero at some point in that interval. when the derivative is zero, we have a stationary point

3. Originally Posted by Apex
Stuck on solving this....
first thing's first, your derivative here is incorrect. fix it

4. Originally Posted by Apex
I don't understand what this means.
just find the x-value for A, which you can do, you know how to find the local minimum point of a function. then just plug in the x-value into g(x) to show that you get the desired result. that is, if $x_1$ is the x-value for the point A, show that $g(x_1) = x$ by plugging it in

5. Originally Posted by Apex
bump
bumping is against the rules. ad you should post new questions in a new thread

6. Hi

These aren't new questions, and they're on the same topic. They're the final questions in the chapter, and I posted them the same day you replied to the other q. Never mind.

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