Question

if 1/f=1/-15+1/-22.5 find f​

Answer 1

Explanation:

$\frac{1}{f} = \frac{1}{ - 15} \frac{1}{ - 22.5} \\ \frac{1}{f} = \frac{15}{225} + \frac{10}{225 } \\ \frac{1}{f} = \frac{15 + 10}{225} \\ \frac{1}{f}= \frac{25}{225} \\ \frac{1}{f} = \frac{1}{9}$

Using Invertendo

f = -9