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