原式=(7x^4-42x²+5x³-30x-5x³-5x)/(x²+1)(x²-6)=(7x^4-42x²-35x)/(x²+1)(x²-6)=7x(x³-6x-5)/(x²+1)(x²-6)=7x(x³+x²-x²-6x-5)/(x²+1)(x...