I'm Lost

[Dez]

my professor give use the problem for a project and want the class to give step by step answer, my problem is that I can't get pass the frist step I no it mite be asking to much but can some one please walk me threw this problem the right way thanks. 1/R=1/R1+1/R2 solve for R

 

[soroban]

Hello, Dez!

\(\displaystyle \text{Solve for }R\!:\;\;\dfrac{1}{R} \:=\:\dfrac{1}{R_1}+\dfrac{1}{R_2}\)

Multiply by \(\displaystyle RR_1R_2\!:\)

. . \(\displaystyle RR_1R_2\left(\dfrac{1}{R}\right) \;=\;RR_1R_2\left(\dfrac{1}{R_1} + \dfrac{1}{R_2}\right) \)

. . . . . . . . \(\displaystyle R_1R_2 \;=\;RR_2 + RR_1\)

. . . \(\displaystyle RR_1+RR_2 \:=\:R_1R_2\)

. . . \(\displaystyle R(R_1+R_2) \:=\:R_1R_2\)

. . . . . . . . . . .\(\displaystyle R \:=\:\dfrac{R_1R_2}{R_1+R_2}\)