(3-х)(х^2+3х+9)-х(х+5)(х-5)=23
( 3 - x)(x^2 + 3x + 9 ) - x(x + 5)(x- 5) = 23 - ( x - 3)(x^2 + 3x + 9) - x(x - 5)(x +5) = 23 - ( x^3 - 27) + x( x^2 - 25) - 23 = 0 - x^3 + 27 + x^3 - 25x - 23 = 0 - 25x = - 4 25x = 4 x = 4/25 x = 0,16