Упростите выражения: a) 3a (a+1) + (a+2) (a-3) b) (y-3) (5-y) - (4-y) (y+6)

a) 3a (a+1) + (a+2) (a-3) =

= 3a^2+3a + a^2-3a+2a-6 =

= 4a^2 + 2a - 6

b) (y-3) (5-y) - (4-y) (y+6) =

= (5y-y^2-15+3y) - (4y+24-y^2-6y) =

= 5y - y^2 - 15 + 3y - 4y - 24 + y^2 + 6y =

= 10y - 39

А) 3 а^2+3 а+а^2+2 а-3 а-6

4 а^2+2 а-6