问题 解答题

(3x-2y-5)(3x+2y-5)-2x(6x+y)-(3x-y)(-y-x)

答案

(3x-2y-5)(3x+2y-5)-2x(6x+y)-(3x-y)(-y-x),

=(3x-5)2-4y2-12x2-2xy+3xy-y2+3x2-xy,

=9x2-30x+25-4y2-12x2-2xy+3xy-y2+3x2-xy,

=-30x+25-5y2

单项选择题
单项选择题