<s>[INST] Did I derive this correctly? I derived this $$(2x+1)^2 \sqrt{4x+1}$$
and got $(8x+4)(\sqrt{4x+1})$+$\frac{2}{\sqrt{4x+1}}(2x+1)^2$
Is this correct?
I ask because Wofram Alpha gave me a different answer. 
Thanks in advance. 
 [/INST] Your answer:
$$\begin{aligned}
&(8x+4)(\sqrt{4x+1})+\frac{2}{\sqrt{4x+1}}(2x+1)^2
\\
=& \frac{(8x+4)(4x+1)}{\sqrt{4x+1}}+\frac{2(2x+1)^2}{\sqrt{4x+1}}
\\
=& \frac{32x^2 + 24x + 4}{\sqrt{4x+1}} + \frac{8x^2 + 8x + 2}{\sqrt{4x+1}}
\\
=& \frac{40x^2 + 32x + 6}{\sqrt{4x+1}}
\\
=& \frac{2(10x + 3)(2x+1)}{\sqrt{4x+1}}.
\end{aligned}$$
WolframAlpha's answer.
</s>