先化简,再求值.已知x=-2,y=125分之一,求x(3x-2y)+(2x+y)²+(2x-y)(x+y)-3(xy+1_数学解答

先化简,再求值.已知x=-2,y=125分之一,求x(3x-2y)+(2x+y)²+(2x-y)(x+y)-3(xy+10)的值

人气：477 ℃　时间：2019-10-23 03:55:35

解答

x(3x-2y)+(2x+y)²+(2x-y)(x+y)-3(xy+10)
=3x^2-2xy+4x^2+4xy+y^2+2x^2+xy-y^2-3xy-30
=9x^2-30
x=-2,
=36-30
=6