mx的平方+2nx-x的平方+6+x=(m-1)x^2+(2n+1)x+6
值与字母x的取值无关,那么有:m-1=0,2n+1=0
m=1,n=-1/2
3m的平方n-1/2n的立方-m的平方n+4n的三次方
=3(-1/2)-1/2(-1/2)^3-1*(-1/2)+4*(-1/2)^3
=-3/2+1/16+1/2-1/2
=-23/16
mx的平方+2nx-x的平方+6+x=(m-1)x^2+(2n+1)x+6
值与字母x的取值无关,那么有:m-1=0,2n+1=0
m=1,n=-1/2
3m的平方n-1/2n的立方-m的平方n+4n的三次方
=3(-1/2)-1/2(-1/2)^3-1*(-1/2)+4*(-1/2)^3
=-3/2+1/16+1/2-1/2
=-23/16