Question

若|m+1/3|+(n-1/2)^2=0,求多项式m^2+2m^3n+n^2-2m^2-2m^3n+3n^2的值

Answer 1

绝对值和平方都大于等于0

相加等于0,若有一个大于0,则另一个小于0,不成立.

所以两个都等于0

所以m+1/3=0,n-1/2=0

m=-1/3,n=1/2

m^2+2m^3n+n^2-2m^2-2m^3n+3n^2

=-m^2+4n^2

=-1/9+1

=8/9