a ( x − 1 ) = 2 ( x − b ) →
→ a · x − a = 2 · x − 2 · b → ( a − 2 ) · x = a − 2 · b
A ( a ) = a − 2 , e B ( a , b ) = a − 2 · b
Posto A ( a ) = 0 → a = 2 , posto B ( a , b ) = 0 → a = 2 · b