Derive Wheatstone Bridge's equation

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Homework Statement



how to derive this equation?
WheatstoneBridge01EqF.gif


and

WheatstoneBridge01EqF2.gif


Homework Equations



WheatstoneBridge01EqE.gif


WheatstoneBridge01EqD.gif


The Attempt at a Solution



I try derive it that to cut out high degree part such as delta_R1*delta_R2
because my teacher told that is very small and near to zero. but I can't made it to that given form. And i think Resistance that have change must be equal like as fraction R1*R3=R2*R4 so (R1+delta_R1)(R2+delta_R2)=(R3+delta_R3)(R4+delta_R4)

Now, I made the last expression to

delta_Vo = [deltaR1/R1-deltaR2/R2+deltaR3/R3-deltaR4/R4]/[2*(1+deltaR3/R3+deltaR4/R4)*(1+(deltaR1+R1)/(deltaR2+R2))]Vs


this is my first time for this forum and my english is not good. so if i do something wrong or someone can't understand me I'm very apologize.

I'd appreciate if someone can help me or tell me if i do wrong way.

Thanks a lot
 

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We need a statement of the problem, namely what are you looking for? What do the symbols that you use stand for? I can understand R1, but what is ΔR1? What about Vg and ΔVg? Are you trying to find how the bridge becomes unbalanced when you change the four resistors by small amounts? You should be providing the details and definitions and we should not be guessing what they are.
 
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