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)/(3x²+6x)
x-6分之x²+1乘以x³＋x分之x²-36
=(x²+1)/(x-6)×(x+6)(x-6)/x(x²+1)
=(x+6)/x
=1+6/x
5x²-4xy分之y²-x²除以5x-4y分之x+y
=(y-x)(y+x)/x(5x-4y)×(5x-4y)/(x+y)
=(y-x)/x
=y/x-1