(8у-х)(6у-х)(6х+4у)+(8у+х)(6у+х)( 6х+4у)

= (48y^2 - 14yx + x^2) (6x + 4y) + (48y^2 + 14xy + x^2) (6x + 4y) =
= (48y^2 - 14yx + x^2 + 48y^2 + 14xy + x^2) (6x +4y) =
= (96y^2 + 2x^2) (6x + 4y) =
= (576y^2x + 384y^3 + 12x^3 + 8yx^2) =
= дальше сам досчитывай. Я тебе сократила

= {6x+4y}{(8x-y)(6y-x)+(8x+y)(6y+x)} = (6x+4y)( 48y^2 + x^2 + x^2 + 48y^2) = 2 * (6x+4y)(48y^2 + x^2)