I need basic Algebra help

Question

I don't know how to solve for this or what the three dots or ellipsis means. I think you have to solve for R = R_p, then plug it into the second equation. Also, I don't see a reason why the (Σ 1/R_i) part is there, does it affect anything? Thanks for the help!

Let R_p = R. If R₁= 50 and R₂ = 25 and I = 0.15, find V.

1/R_p=(1/R₁ + 1/R₂ + 1/R₃ + ... +1/R_i)=Σ 1/R_i

V=IR

Answer 1

this is more of an electrical engineering problem than an algebra problem, but lots of overlap

1/Rp = 1/R1 + 1/R2 = 1/50 + 1/25 = .02 + .04 = .06 this is how you calculate total resistance in a parallel circuit.

1/Rp = .06

Rp = 1/.06 = 16 2/3 ohms

V = IR = .15 amperes x (16.666...ohms) = .15/.06 = 0.9375 volts the "..." after 16.666... means the 6's go on forever

in 1/Rp = 1/R1 + 1/R2 + 1/R3 + ... + 1/Ri = sum of 1/Ri where the three dots, "..." mean there are an unknown number of other R's, such as + 1/R4 + 1/R5 + 1/R6 ... ending at any unspecified 1/Ri

the last i is how many parallel circuits there are. most would probably use Rt instead of Rp for total resistance.