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Can you make a the subject of the formula?

Can someone please show me how to make a the subject of the formula. It must be simple, I just can't do it!!!

R = (ab) / (a+b)

6 Answers

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  • Anonymous
    1 decade ago
    Favourite answer

    times both sides by (a+b)

    R(a+b) = ab

    divide by R

    (a+b) = (ab)/R

    take a from each side

    b = (ab)/R - a

    times both sides by R

    Rb = ab - Ra

    a(b - R) = Rb

    a = (Rb)/(b-R)

  • 1 decade ago

    The Ideal Solution for It:

    1 / R = a / (ab) + b / (ab) ; Reversing the Whole equation

    => 1 / R = 1 / b + 1 / a

    => 1 / a = 1 / R - 1 / b

    1 / a = (b - R) / Rb

    => a = (b - R) / Rb

  • 1 decade ago

    Hi.

    R = (ab) / (a + b)

    1. Multiply both sides by (a + b)

    Your equation will now look like this;

    R(a + b) = ab

    2. Simplify this, you should get;

    Ra + Rb = ab

    3. Ra = ab - Rb

    4. Devide both sides by R

    You should get the value of a which is;

    a = ab - Rb / R

    Good Luck!

    Source(s): I study Math too
  • Anonymous
    1 decade ago

    Rewrite this as R/1 = (ab)/(a+b)

    Now, cross-multiply:

    R (a+b) = ab

    Distribute on the left:

    Ra + Rb = ab

    Subtract Rb from both sides:

    Ra = ab - Rb

    Subtract ab from both sides:

    Ra - ab = -Rb

    Factor on the left:

    a(R-b) = -Rb

    Divide both sides by (R-b):

    a = (-Rb)/(R-b)

  • 1 decade ago

    R(a+b) =ab

    a(R-b) + Rb =0

    a = Rb/(b-R)

  • 1 decade ago

    a= (ab/ R) - b

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