$\uparrow \uparrow \uparrow \uparrow \uparrow$ $$ $(a+b)^2$ $$ $${\oint }_C\vec{B}\circ \mathrm{d}\vec{l}={\mu }_0(I_{\text{enc}}+{\epsilon }_0\frac{\mathrm{d}}{\mathrm{d}t}{\int }_S\vec{E}\circ \widehat{n}\mathrm{d}a)$$ $1\frac{2}{3}$ ${}_6{}_8{}^{9}1_2^3{}^5$ $\frac{1}{2}$