m+n=1,mn=1/2,求1/4m²-1/2mn+1/4n²

问题描述:

m+n=1,mn=1/2,求1/4m²-1/2mn+1/4n²

1/4m²-1/2mn+1/4n²
=(1/2m-1/2n)2
=1/4(m-n)2
=1/4[(m+n)2-4mn]
=1/4(1-2)
=-1/4