# Math Help - Rearrange make subject

1. ## Rearrange make subject

Rearrange to make M the subject
1/M = 1/M1 + 1/M2

2. $
\frac{1}{m}=\frac{m_{2}+m_{1}}{m_{1}m_{2}}
$

$
m=\frac{m_{1}m_{2}}{m_{2}+m_{1}}
$

Can you explain to me why it is arranged like that please?

4. $\frac{1}{m}=\frac{1}{m_{1}}+\frac{1}{m_{2}}=\frac{ m_{2}}{m_{1}m_{2}}+\frac{m_{1}}{m_{2}m_{1}}$
you have the same denominator,
$\frac{1}{m} =$ $\frac{1}{m_{1}}+\frac{1}{m_{2}}=\frac{m_{2}+m_{1}} {m_{2}m_{1}}$
to find m just flip the fraction,
$m=\frac{m_{2}m_{1}}{m_{2}+m_{1}}$
hope it helps.

5. ## Hello

Thanks

Originally Posted by Raoh
$\frac{1}{m}=\frac{1}{m_{1}}+\frac{1}{m_{2}}=\frac{ m_{2}}{m_{1}m_{2}}+\frac{m_{1}}{m_{2}m_{1}}$
you have the same denominator,
$\frac{1}{m} =$ $\frac{1}{m_{1}}+\frac{1}{m_{2}}=\frac{m_{2}+m_{1}} {m_{2}m_{1}}$
to find m just flip the fraction,
$m=\frac{m_{2}m_{1}}{m_{2}+m_{1}}$
hope it helps.