c ' (x) = 4x - 3
$$\overline{c}=\frac{2x^2-3x+8}{x}= 2x-3+\frac{8}{x}$$
$$\overline{c} ' = 2-\frac{8}{x^2}$$
$$ε_c(x)=c'(x)*x/c = \frac{4x^2-3x}{2x^2-3x+8}$$
2. 4x-3 = 2x-3 + 8/x
<=> 2x = 8/x
<=> x = 2 ( x positiv ! )
Also Punkt ( 2 ; 10 ) .
$$ε_c(2)= \frac{10}{10}=1$$
3. $$\overline{c} ' (x)= 0$$ $$<=> 0= 2-\frac{8}{x^2}$$ $$ <=> 2= \frac{8}{x^2}$$<=> x^2 = 4 wegen x>0 also x=2 .
hinreichende Bedingung für Min:
\( \overline{c} '(x) = 0 \) und \( \overline{c} ''(x) >0 \)
erfüllt, wegen \( \overline{c}''(x) = \frac{16}{x^3} \) und \( \frac{16}{8} = 2 \gt 0 \).