303. Find the derivative of the function $y=0.5^{\sin 4 x}$.
Solution. $\quad y^{\prime}=0.5^{\sin 4 x} \ln 0.5(\sin 4 x)^{\prime}=0.5^{5 \sin 4 x} \ln 0.5 \cdot \cos 4 x \cdot 4=$ $=4 \cos 4 x \cdot 0.5^{\sin 4 x} \ln 0.5$.