(a4b3x2y - u2v5x2y + a4b3xy2 - u2v5xy2 ) / (u2v5xy - a4b3xy - u2v5x2y2 + a4b3x2y2 )
= (xy(a4b3x - u2v5x + a4b3y - u2v5y )) / (xy (u2v5 - a4b3 - u2v5xy + a4b3xy ) )
= (a4b3x - u2v5x + a4b3y - u2v5y ) / (u2v5 - a4b3 - u2v5xy + a4b3xy )
= (x(a^4 b^3 -u^2 v^5 ) + y(a^4 b^3 - u^2 v^5)) /(-(a^4 b^3- u^2 v^5) + xy(a^4 b^3 - u^2 v^5))
= ((a^4 b^3 -u^2 v^5 )(x + y)) /((a^4 b^3- u^2 v^5)(xy-1))
= (x+y)/(xy-1)
Ohne Berücksichtigung der Spezialfälle, d.h. unter der Bedingung, dass xy((a^4 b^3- u^2 v^5)≠0 und xy≠1