若丨2x-5丨+(2x-5y+20)^2=0,求代数式(-2x^2)-2x(5y-2x)=3y(6x-5y)-3y(4x-5y)的值

若丨2x-5丨+(2x-5y+20)^2=0∴2x-5=0;x=5/2;2x-5y+20=0;y=5;(-2x^2)-2x(5y-2x)-3y(6x-5y)-3y(4x-5y)=-2x²-10xy+4x²-18xy+15y²-12xy+15y²=2x²+30y²-40xy=2*(25/4)+30*25-40*(5/2)*5=25/...