4.(1)(-2 x+3)(-2x-3)=-(-2x+3)(2x+3)=-(-4x^2+9)=4x^2-9
⑵(-x／2+2y)^2=x^2／4-2xy+4y^2
(3)-2(x／3-3y／2)^2=-2(x^2／9-xy+9y^2／4)=-2x^2／9+2xy-9y^2／2
⑷4(-3x／2-3y)(3x／2-3y)=-4(3x／2+3y)(3x／2-3y)=-4(9x^2／4-9y^2)=-9x^2+36y^2
⑸9m^2n^2-1／4-m^2n^2=8m^2n^2-1／4
(8)(x／2+5+x／2-5)(x／2+5-x／2+5)=10x
(7)(x+2y)^2-9z^2
(6)x^2-(x^2-4)=4