The lowest form of (a + b)ab − 2(a + b) if ab=1.
(a2 + b2)(a + b)
Here the algebraic fraction is (a + b)ab − 2(a + b)
It can be reduced to ((a + b)2 − 2ab)(ab)×(a + b)
Since ab=1, it'll be again reduced to ((a + b)2 − 2ab)(a + b)
[we have known that (a + b)2 = a2 + 2ab + b2 ]
So, the reduced form is (a2 + b2)(a + b)