第1个回答 2015-12-12
(4) (m+n)^2-4m(m+n)+4m^2
=m^2+2mn+n^2-4m^2-4mn+4m^2
=m^2-2mn+n^2.
(5) a^2+2a(b+c)+(b+c)^2
=a^2+2ab+2ac+b^2+2bc+c^2
=a^2+b^2+c^2+2ab+2bc+2ac.
=m^2+2mn+n^2-4m^2-4mn+4m^2
=m^2-2mn+n^2.
(5) a^2+2a(b+c)+(b+c)^2
=a^2+2ab+2ac+b^2+2bc+c^2
=a^2+b^2+c^2+2ab+2bc+2ac.
第2个回答 2015-12-12
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