2.5 Lösning 5a
Från Mathonline
\[ \displaystyle y = {e\,^x + e\,^{-x} \over 2} = {e\,^x \over 2} + {e\,^{-x} \over 2} = {1 \over 2}\cdot e\,^x + {1 \over 2}\cdot e\,^{-x}\]
\[ \displaystyle y\,' = {1 \over 2}\cdot e\,^x - {1 \over 2}\cdot e\,^{-x} = {e\,^x - e\,^{-x} \over 2} \]
