Thursday, December 25, 2014

Solve for x, a/(ax-1) + b/(bx-1) = a+b

a/ax-1 + b/bx-1 =
a+b


=> ( a- ax) / ax  + ( b-bx)/ bx = (a+
b)


We will multiply by
abx^2


==> (a- ax)(b-bx) = (a+b)
abx^2


==> (ab - 2abx + abx^2 = (a+b)
abx^2


==> ab - 2abx = (a+b)( abx^2) -
abx^2


We will facro abx^2 from the right
side.


==> ab -2abx = abx^2 ( a+b
-1)


We will factor ab from the left
side.


==> ab ( -2x +1) = abx^2 ( a+
b-1)


Now we will divide by
ab.


==> (-2x+1) = x^2 ( a+ b
-1)


==> (a+b-1) x^2 +2x -1 =
0


Now we have a quadratic equation, we will solve for x in
terms of a and b.


==> x1= ( -2 + sqrt(4 +4(a+b-1) /
2(a+b-1)


            = ( -2+ 2sqrt(a+b) /
2(a+b-1)


           = (-1+ sqrt(a+b) /
(a+b-1)


==>x1= (-1+ sqrt(a+b) /
(a+b-1)


==> x2= ( -1-
sqrt(a+b) / (a+b-1)

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