3x³-2y³-6x²y² +xy = (3x³ -6x²y²) + (xy -2y³)= 3x²(x-2y²) +y(x-2y²)=
= (3x² +y)(x-2y²)
при х=2/3 ; у=1/2
(3 * (2/3)² + 1/2) *(2/3 - 2*(1/2)² ) = (4/3 + 1/2)(2/3 - 1/2) =
= (8/6 + 3/6) * (4/6 - 3/6) = 11/6 * 1/6 = 11/12
ответ : 11/12
х²у -у+у²х-х = xy(x+y) - (x+y) = (xy-1)(x+y)
x =4 ; у =0,25
(4*0,25 - 1)(4+0,25) = (1 - 1) * 4,25 = 0 * 4,25 = 0
ответ: 0 .