Watch for dimensional inconsistencies!

You cannot add 1/R to R.

 

@MrChips

got it, my bad, will correct it at once

 

@MrChips



I suspect its not right, due to my answer: -100.59 Ohms

 

Still having dimensional inconsistencies!

You cannot have R*R - R.

You cannot have R + 1.
Units of R is resistance.
1 has no units.

 

@MrChips I corrected my calculation. Now I get R1 = 1000 Ohms

 

You still have R1 on the right hand side of the equation.

 

You still have R1 on the right hand side of the equation.

Now, I got R1 all by itself, inserted the numbers and got R1 = 1000 Ohms

 

Your equation appears to be correct.
I don't know what values you have been given.

 

Your equation appears to be correct.
I don't know what values you have been given.

In my problem it stood Im supposed to use R3 and R_ab to calculate the value for Rpt ( Rpt = R1 and R3 in your posted circuit).
R3 = 1200 Ohms
R_ab = 1138 Ohms

 

If R1 = R3
and
R2 = R4 = 1200

then solving for R1 and R3 is much simplified.

Rab = (R1 + R2) / 2
R1 = R3 = 2 x Rab - R2

 

@MrChips

Thats the same equation I got to in my #12 post, maybe my writing is kinda off. Thank you so much for your assistance through this day, the same goes for @ericgibbs , @MrAl . Much appreciated!