(3+2x)^2​​ −3,6x(3x+4) при x=2,5

9+4x^2+12x-10.8x^2-14.4x=-6.8x^2+9-2.4x=>  x=2.5=>  -6.8*6.25+9-2.4*2.5=-33.5-6=-39.5