已知x+y=1,xy=-0.5,利用因式分解求值：（x+y）（x-y）y-x（x+y)@_数学解答

已知x+y=1,xy=-0.5,利用因式分解求值：（x+y）（x-y）y-x（x+y)@

人气：351 ℃　时间：2020-06-03 00:59:01

解答

(x+y)(x-y)y-x(x+y)^2
=(x+y)[(x-y)y-x(x+y)]
=(x+y)(xy-y^2-x^2-xy)
=-(x+y)(x^2+y^2)
=-(x+y)[(x+y)^2-2xy]
=-1*[1^2-2*(-0.5)]
=-1*2
=-2