Odd, \boldmath doesn't work on the forums. I will investigate this matter further.
Edit: It appears the forums is using some strange version of LaTeX... give me some time lol.
Edit 2: \pmb{} works, but it makes it UBER bold and ugly. Let me try and find a working normal bold font on this forum before resorting to that.
Edit 3: I've updated my old post with another version underneath, but the x does not have the nice curves on it when bolded, something that frustrates me immensely. I'm looking for a fix now.
Edit 4: Fu**ing finally. Got it. Posting the nice version here
This is the LaTeX code for the above statement: \frac{d}{dx}[\sin(3x+1)]=\mathbf{3\boldsymbol{\cos}(3\textbf{\textit{{x}}}\boldsymbol{+}1)}
This is the LaTeX code for the below statement:
\frac{d}{dx}[\sin(3x+1)]=\mathbf{{\boldsymbol{\cos}(3\textbf{\textit{{x}}}\boldsymbol{+}1)\times3}}
Now, having succeeded in that, I am going to bed as it's 2:30 in the morning. Goodnight gentlemen. Enjoy your bolded, pretty equation