Question

if u= -12,f=-4 find v​

Answer 1

we know that:-

$\tt \huge \bigstar \fbox{ \frac{1}{f} = \frac{1}{u} + \frac{1}{v}}$

Now,

$\tt \huge \mapsto \: \frac{1}{v} = \frac{1}{f} - \frac{1}{u} \\ \\ \tt \huge \mapsto \:\frac{1}{v} = \frac{1}{ - 12} - \frac{1}{ - 4} \\ \\ \tt \huge \mapsto \: \frac{1}{v} = \frac{ - 4 - ( - 12)}{48} \\ \\ \tt \huge \mapsto \: \frac{1}{v} = \frac{ - 4 + 12}{48} \\ \\ \tt \huge \mapsto \: \frac{1}{v} = \frac{8}{48} \\ \\ \tt \huge \mapsto \: \frac{1}{v} = \frac{1}{6} \\ \\ \tt \huge \boxed {\mapsto \:v = 6}$