问题
计算题
(3x﹣2y﹣5)(3x+2y﹣5)﹣2x(6x+y)﹣(3x﹣y)(﹣y﹣x)
答案
解:(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)
解:(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.