$\mathop {\lim }\limits_{x \to 0} \frac{\left(7^x-1\right)^4}{\tan \left(\frac{x}{\mathrm{k}}\right) \cdot \log \left(1+\frac{x^2}{3}\right) \cdot \sin 4 x}=3(\log 7)^3$, then $\mathrm{k}=$

If $x^y+y^x=\mathrm{a}^{\mathrm{b}}$, then $\frac{\mathrm{d} y}{\mathrm{~d} x}$ at $x=1, y=2$ is

The value of $\frac{(\cos \theta+i \sin \theta)^4}{(\sin \theta+i \cos \theta)^5}=$ where $\mathrm{i}=\sqrt{-1}$

If $\mathrm{f}(x)=2 x^3+\mathrm{m} x^2-13 x+\mathrm{n}$ and 2,3 are the roots of the equation $\mathrm{f}(x)=0$ then the value of $4 m+5 n$ is