(1) (5a-1/2b^2)-(5a-b^2)
问题描述：
(1) (5a-1/2b^2)-(5a-b^2)
(2) (x+y+z)(x+y-z)
(3) (9x^3y^2-6x^2y+3xy^2)/(-3xy)
答
(1) (5a-1/2b^2)-(5a-b^2)
=5a-1/2b^2-5a+b^2
=1/2b^2
(2) (x+y+z)(x+y-z)
=(X+Y)^2-Z^2
(3) (9x^3y^2-6x^2y+3xy^2)/(-3xy)
=-3X^2Y+2X-Y