化简求值:9x²-6xy+y²分之3x²-xy其中x=2分之1,y=-3分之2
问题描述:
化简求值:9x²-6xy+y²分之3x²-xy其中x=2分之1,y=-3分之2
答
原式
=x(3x-y)/(3x-y)²
=x/(3x-y)
=(1/2)/[3*(1/2)-(-2/3)]
=(1/2)/(3/2+2/3)
=(1/2)/(13/6)
=1/2x6/13
=3/13 (13分之3)