1/R = 1/R1 1/R2 for R1 ( Electric circuit)

Question

1/R = 1/R1 1/R2

for R1 ( electric circuit)

Answer 1

1/R = 1/R1  + 1/R2

so  1/R -1/R2 =1/R1

( r2 -r )/ (r * r2) =  =1/R1

now do reciprocal of both sides

(r * r2) /( r2 -r ) = R1

Answer 2

What is the question?

Can't help you unless I know what you want to know.

And you left out a +

1/R = 1/R1 + 1/R2

easier to use is

R = r1*r2/(r1+r2)

rereading, do you mean "solve for R1"? Adding that word "solve' makes it so much more easier to understand!

R1 = R*R2/(R-R2)

.

Answer 3

Well, there's several ways to go about solving for R1

1/R = 1/R1 + 1/R2  (Substract 1/R2 from both sides of the equation).

1/R - 1/R2 = 1/R1

Thus, 1/R1 = 1/R - 1/R2

Now, you have to find the common denominator for the 1/R - 1/R2.  You will need to cross multiply in order to get:

1/R1 = ((R2 - R) / (R2 x R))

Then, you want to invert your equation.

R1 = ((R2 x R) / (R2 - R))

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Another approach:

R = ((R1 x R2) / (R1 + R2))

solving for R1:

multiply both sides of the equation by (R1 + R2)

R(R1 + R2) = R1 x R2

dividing through by R

(R1 + R2) = (R1 x R2) / R

substract R2 from both sides:

R1 = ((R1 x R2) / R) - R2

find the common denominator for the right side

R1 = (R1 x R2 - R x R2) / R

Factor out R2

R1 = R2 x (R1 - R) / R

divide both sides by (R1 - R)

R1 / (R1 - R) = R2 / R

invert the equation

(R1 - R) / R1 = R / R2

then R1 / R1 is just 1

(R1 / R1) - R / R1 = R / R2

1 - R / R1 = R / R2

substract 1 from both sides of the equation.

-R / R1 = R / R2 - 1

-R / R1 = (R / R2) - R2 / R2

then find the common denominator on the right side of the equation.

-R / R1 = (R - R2) / R2

cross multiply to get

R x R2 = R1 x (R - R2)

solve for R1

R1 = (R x R2) / (R - R2)

It's a bit tricky, but there it is.