10xy^2-12x^2y+9x^2y-9xy^2,если x=1/3,y=9

= ( 10хy^2 - 9xy^2 ) - ( 12x^2y - 9x^2y ) = xy^2 - 3x^2y = xy•( y - 3x ) X = 1/3 ; y = 9 1/3•9•( 9 - 3•1/3 ) = 3•( 9 - 1 ) = 3•8 = 24 Ответ 24