2x(x^2+7)-2(x+1)-4x=(2x-3)(x^2+4)+3x^2-k

Question

2x(x^2+7)-2(x+1)-4x=(2x-3)(x^2+4)+3x^2-k

Answer 1

2x^3+14x-2x-2-4x=2x^3+8x-3x^2-12+3x^2-x
2x^3-2x^3+3x^2-3x^2+14x-2x-4x-8x+x=2-12
x=-10