Hallo,
Text erkannt:
\( \begin{array}{l} N(t)=20-15 e^{-0,2231 t} \\ N^{\prime}(t)=3,3465 e^{-0,2231 t} \end{array} \)
a)
\( \begin{array}{l} 15=20-15 e^{-0,2231 t} \\[10pt] -5=-15 e^{-0,2231 t} \\[10pt] \frac{1}{3}=e^{-0,2231 t} \\[10pt] \ln \left(\frac{1}{3}\right)=-0,2231 t \\[10pt] 4,92=t \end{array} \)
b)
c) \( N^{\prime}(1)=3,3465 e^{-0,2231} \approx 2,68 \)