第2个回答 2015-05-03
12。m(m+n)(m-n)-m(m+n)^2
=m(m+n)[(m-n)-(m+n)]
=m(m+n)(-2n)
=-2mn(m+n)
当 m+n=1, mn=-1/2时,
原式的值=-2x(-1/2)x1
=1。
13。原式=2001x(2002x10000+2002)-(2002x10000+2001)x2002
=2001x2002x10000+2001x2002-2002x10000x2002-2001x2002
=2001x2002x10000-2002x2002x10000
=2002x10000x(2001-2002)
=-20022002.本回答被网友采纳