化简求值的一道初一数学题

x⒉+y⒉+5/4=2x+y,
x⒉+y⒉+5/4-2x-y=0
(x-1)^2+(y-1/2)^2=0
所以x=1，y=1/2

（6x⒊y⒉-12x⒉y⒉+3x⒉y⒊)/(-9xy)
=3xy(2x^2y-4xy+xy^2)/(-9xy)
=(-2x^2y+4xy-xy^2)/3
=xy(-2x+4-y)/3
=1*1/2*（-2+4-1/2）/3
=1/4

x⒉+y⒉+5/4=2x+y
x^2-2x+1+y^2-y+1/4=0
(x-1)^2+(y-1/2)^2=0
则x=1 y=1/2
6x⒊y⒉-12x⒉y⒉+3x⒉y⒊)/(-9xy)
=3x^2y^2(2x-4+y)/(-9xy)
=-1/3*xy(2x+y-4)
=-1/3*1*1/2(2+1/2-4)
=1/4

2/3