CAS Problem

[Richard112]

Hey,
I have a question which requires me to equate a derivative equal to zero, but my CAS (TI-nspire cx) is giving me an answer in terms of the variable. I've used online calculators and they seem to give the correct answer.

Anyone know how to fix this problem? I've attached the question for reference.

Cheers   

[vox nihili]

I just tried it on a ti-nspire and didn't have any trouble.

Syntax I used was:

d/dx(SA)
solve(ANS=0,x)

Answer I got was 11.33

[Richard112]

I just tried it on a ti-nspire and didn't have any trouble.

Syntax I used was:

d/dx(SA)
solve(ANS=0,x)

Answer I got was 11.33

I tried again, no luck :/
The answer I got was "(x^3-1500)*sqrt(x^6+4000000)+x^6=2000000".


Third time, I got it. Thanks--for some reason, using your syntax worked, but using ctrl + c to copy the answer and solving equal to 0 didn't.

[AlphaZero]

Could to show us exactly what your CAS inputs were so that we can figure out what went wrong? (We don't want this to happen again)

If I was doing that question, my CAS inputs would look something along the lines of these: \begin{align*}&\texttt{Define }\;a(x)=\frac{6000}{x}+2x\cdot\left(x+\sqrt{\left(\frac{2000}{x^2}\right)^2+x^2}\right)\\
&\texttt{solve}\!\left(\frac{d}{dx}\big(a(x)\big)=0,x\right)\\
&\vdots\quad \text{(further inputs to answer the rest of the question)} \end{align*} (Note: there are many ways to go about using the CAS, but the one above is the most general and is quite efficient).