x²+4x+4分之x²-4y²乘以3x²+6xy分之x+2=（x+2y)(x-2y)/(x+2)²×(x+2)/3x(x+2y)=(x-2y)/3x(x+2)=(x-2y)(3x²+6x)x-6分之x²+1乘以x³＋x分之x²-36 =(x²+1)/(x-6)×(x+...