Разложите на множители а) 45a+6b-3ab-90 б) ac^4-c^4+ac^3-c^3 в) a-b+a^2-b^2

а). 45 a + 6 b - 3 a b - 90 = (45 a - 3 a b) - (90 - 6 b) = 3 a (15 - b) - 6 (15 - b) =

= (15 - b) (3 a - 6);

б). a c^4 - c^4 + a c³ - c³ = c³ (a c - c + a - 1) = c³ [ (ac - c) + (a - 1) ] =

=c³ [c (a - 1) + (a - 1) ] = c³ (a - 1) (c + 1);

в). a - b + a² - b² = (a - b) + (a² - b²) = (a - b) + (a - b) (a + b) = (a - b) (1 + a + b).