四道初一计算题 （1）(8x³-12x²+16x)÷(-4x)（2）[3（m+n)(m-n)+(m-

1、(y^2+2)^2-(y+2)(y-2)(y^2+4)
=(y^2+2)^2-(y^2-4)(y^2+4)
=y^4+4-y^4+16
=4y^2+20
2、(x+y)(y-x)-(2+y^2)(1-x)
=y^2-x^2-2+2x-y^2+xy^2
=xy^2-x^2+2x-2
3、(m+2)(m-2)(m^2-2m+4)(m^2+2m+4)
=(m^2-4)(8m^2+16)
=8(m^4-2m^2-8)
=8(m^2-4)(m^2+2)
=8(m^2+2)(m+2)(m-2)
4、（x+y)(x-y)+(y-z)(y+z)+(z-x)(x+z)
=(x^2-y^2)+(y^2-z^2)+(z^2-x^2)
=0