Разложите на множители:

а) (а+3) (b+5) - (a+3) (b+6)

б) (3a+10) (6c-5a) - (8a-9) (5a-6c)

(а+3) (b+5) - (a+3) (b+6) = (a+3) ((b+5) - (b+6)) = (a+3) (b+5-b-6) = - (a+3)

(3a+10) (6c-5a) - (8a-9) (5a-6c) = (3a+10) (6c-5a) + (8a-9) (6c-5a) =

= (6c-5a) (3a+10+8a-9) = (6c-5a) (3a+8a+1)