而(2-x) (4-y)二8-4x-2y xy=8-(4x 2y) 2=10- (4x 2y) =10- (4x —) 而(2-x) (4-y)二8-4x-2y xy=8-(4x 2y) 2=10- (4x 2y) =10- (4x —) 发布时间:2025-08-09 22:29:34