(а+7)^2+(а-7)(а+7)+12а-2x(1-x)+(2x-3)^2(5x-1)^2-25x^2=

(a+7)²+(a-7)(a+7)+12a-2x(1-x)+(2x-3)²*(5x-1)²-25x² = a2+14a+49+12a-2x+2x²+((2x-3)(5x-1))²-25x² = a²+14a+a²+12a-2x+2x²+(10x²-2x-15x+3)²-25x² = a²+14a+a²+12a-2x+2x²+(10x²-17x+3)²-25x² = a²+14a+a²+12a-2x+2x²+100x⁴+289x²+9-340x³+60x²-102x-25x² = 2a²+26a-104x+326x²+100x⁴+9-340x³