下列运算中不正确的是( )
A.3xy-(x2-2xy)=5xy-x2 | B.5x(2x2-y)=10x3-5xy |
C.5mn(2m+3n-1)=10m2n+15mn2-1 | D.(ab)2(2ab2-c)=2a3b4-a2b2c |
计算:
(1)
(2)(x2y+3)(x2y-3)
(3)(3mn+1)(3mn-1)-8m2n2
(4)(x+3y-2)(x-3y-2)
(1)

(2)(x2y+3)(x2y-3)
(3)(3mn+1)(3mn-1)-8m2n2
(4)(x+3y-2)(x-3y-2)