sqrt(x)+sqrt(y)-4x+y+4+1/4=0=sqrt(x-2)+sqrt(y+1/2)
即sqrt(x-2)=0;sqrt(y+1/2)=0
即x=2;y=-1/2
y^(-x+3xy)=(-1/2)^(-2+3*2(-1/2))=-32
sqrt是平方的意思,x^y是 x的y次方