x^5*y^2*c(2,7)<=x^4*y^3*c(3,7)又x^4*y^2>0所以x*c(2,7)<=y*c(3,7),化简得3x<=5(2-x)所以8x<=10,x<=1.25又xy=x(2-x)<0,所以x>2或x<0综上得x<0