问题
计算题
化简
(1)x2y﹣3xy2+2yx2﹣y2x
(2)(7m2n﹣5mn)﹣(4m2n﹣5mn)
答案
解:(1)x2y﹣3xy2+2yx2﹣y2x,
=(x2y+2yx2)+(﹣3xy2﹣y2x),
=3x2y﹣4xy2;
(2)(7m2n﹣5mn)﹣(4m2n﹣5mn),
=7m2n﹣5mn﹣4m2n+5mn,
=(7m2n﹣4m2n)+(﹣5mn+5mn),
=3m2n.
化简
(1)x2y﹣3xy2+2yx2﹣y2x
(2)(7m2n﹣5mn)﹣(4m2n﹣5mn)
解:(1)x2y﹣3xy2+2yx2﹣y2x,
=(x2y+2yx2)+(﹣3xy2﹣y2x),
=3x2y﹣4xy2;
(2)(7m2n﹣5mn)﹣(4m2n﹣5mn),
=7m2n﹣5mn﹣4m2n+5mn,
=(7m2n﹣4m2n)+(﹣5mn+5mn),
=3m2n.