Selesaikan {l}{f1/a+1/b=1/ctext{and}ab=c,text{whatistheaverageof}}{{ccccc}{0}&{text{b)}1/2}&{text{c)}1}&{text{d)}}}

$$\left. \begin{array} { l } { f \frac { 1 } { a } + \frac { 1 } { b } = \frac { 1 } { c } \text { and } a b = c , \text { what is the average of } } \\ { \left. \begin{array} { c c c c c } { 0 } & { \text { b) } \frac { 1 } { 2 } } & { \text { c) } 1 } & { \text { d) } } \end{array} \right. } \end{array} \right.$$

Selesaikan untuk f, a, b, c

$$f=\frac{a\left(b-c\right)}{bc}$$

$$a\neq 0$$

$$b\neq 0$$

$$c\neq 0$$