x²+xy/(x-4y)(x+y),其中x=4,y=-1

问题描述:

x²+xy/(x-4y)(x+y),其中x=4,y=-1

x²+xy/(x-4y)(x+y)
=x(x+y)/(x-4y)(x+y)
=x/(x-4y)
=4/(4+4)
=1/2