已知丨m-2丨+(n+1/5)²=0,求m-(m²n+3m-4n)+3(2nm²-3n)的值∵丨m-2丨+(n+5/1)²=0∴m-2=0 m=2n+1/5=0 n=-1/5m-(m²n+3m-4n)+3(2nm²-3n)=m-m²n-3m+4n+6nm²-9n=-2m-5n+5m²n...