已知：a=½m-2n+1,b=½m-2n+3,c= - 知识问答

已知：a=½m-2n+1,b=½m-2n+3,c=½m-2n+2.求值:a方+b方+c方-

4个回答

a-b=-2,b-c1,c-a=1
a方+b方+c方-ab-ac-bc
=(1/2)[a^2+b^2-2ab+b^2+c^2-2bc+c^2+a^2-2ac]
=((1/2)[(a-b)^2+(b-c)^2+(c-a)^2]
=(1/2)[4+1+1]
=(1/2)6=3
a方+b方+c方-ab-ac-bc的值为3.

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