约分 16-x²分之4x-x² 3x²+6xy+3y²分之x²-y平方 16-x²分之4x-x²3x²+6xy+3y²分之x²-y
问题描述：
约分 16-x²分之4x-x² 3x²+6xy+3y²分之x²-y平方
16-x²分之4x-x²
3x²+6xy+3y²分之x²-y
答
(4x-x^2)/(16-x^2)
=x(4-x)/(4+x)(4-x)
=x/(4+x)
(x^2-y^2)/(3x^2+6xy+3y^2)
=(x-y)(x+y)/3(x+y)^2
=(x-y)/3(x+y)
答
16-x²分之4x-x² =x(4-x)/[(4-x)(4+x)]=x/(x+4)
3x²+6xy+3y²分之x²-y平方
=(x+y)(x-y)/[3(x+y)²]
=(x-y)/﹙3x+3y)