Need help in Aptitude Question

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
anyway you put Rpq=Req right?
We're way past that! -- Please concentrate! -- You're almost there!!!:cool:

but why, i forgot. because it is infinite ?
 

Thread Starter

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Req = (Req - 2Ω)(1Ω + Re
q)

let Req =x
x=(x-2)(x+1)
x=x2 +x -2x -2
x2+x-x-2x-2=0
x2-2x-2=0

For ax^2+bx+c=0
x=(-b±√(b^2-4ac))/2a


a=1, b=-1,c=-1
 

WBahn

Joined Mar 31, 2012
32,823
(1Ω x Req) = (Req - 2Ω)(1Ω + Req)
(1Ω x Req) = Req+Req2-2Ω-2Req
Req-Req = Req2-2Req -2Ω
Req2-2Req -2Ω=0
Don't write Req² as Req2. That appears either like a different quantity -- the resistance eq2 -- or as Req multiplied by two. The normal text expression is to use the carat symbol, '^', for exponentiation.

And, once again, start tracking your units!

(1 Ω)(Req) = (Req)(1 Ω) + (Req)^2 - (2 Ω)(1 Ω) - (2 Ω)(Req)
(Req)(1 Ω) + (Req)^2 - (2 Ω²) - (2 Ω)(Req) - (1 Ω)(Req) = 0
(Req)^2 + (Req)(1 Ω) - (2 Ω)(Req) - (1 Ω)(Req) - (2 Ω²) = 0
(Req)^2 + (Req)[1 Ω - 2 Ω - 1 Ω] - (2 Ω²) = 0
(Req)^2 - (2 Ω)(Req) - (2 Ω²) = 0

If I can be bothered to take the time to do it properly, why can't you?

Now apply the quadratic formula, ask yourself which of the two solutions makes sense, and you are done.
 
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