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

б)5у-15-у^2+3у-4у+у^2-24+6н10у-39

а)3а^2+3а+а^2+2а-3а-64а^2+2а-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