а) (х-5)(9-х) = 9х - х^2 - 45 + 5х = -x^2 + 14x - 45
б) (-8-а)(b+2) = -8b - 16 - ab - 2a = - ab - 8b - 2a - 16
в) (у-10)(-у+6) = -y^2 + 6y + 10y - 60 = -y^2 + 16y - 60
г) (-7-b)(a-4) = -7a + 28 - b - 4b = -7a - b - 4b + 28
а) (х-5)(9-х) = 9х - х^2 - 45 + 5х = -x^2 + 14x - 45
б) (-8-а)(b+2) = -8b - 16 - ab - 2a = - ab - 8b - 2a - 16
в) (у-10)(-у+6) = -y^2 + 6y + 10y - 60 = -y^2 + 16y - 60
г) (-7-b)(a-4) = -7a + 28 - b - 4b = -7a - b - 4b + 28