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一、分与合例 1 设ａ2 ｂ2 1ｂ2 ｃ2 +1ｃ2 ｄ2 +1ｄ2 ａ2 -ｂ2 ｃ21ｃ2 ｄ2 +1ｄ2 ａ2 +1ａ2 ｂ2 +ｃ2 ｄ2 1ｄ2 ａ2 +1ａ2 ｂ2 +1ｂ2 ｃ2 -ｄ2 ａ2 1ａ2 ｂ2 +1ｂ2 ｃ2 +1ｃ2 ｄ2 =0 .①求证 :ａｂ+ｂｃ+ｃｄ +ｄａ与ａｂ +ｃｄ -ｄａ -ｂｃ中至少有一个为零 .讲解 这是文
One, divide and match example 1 Let a2 b2 1b2 c2 +1c2 d2 +1d2 a2 -b2 c21c2 d2 +1d2 a2 +1a2 b2 +c2 d2 1d2 a2 +1a2 b2 +1b2 c2 -d2 a2 1a2 b2 +1b2 c2 +1c2 d2 =0 .1 Prove that at least one of ab+bc+cd+da and ab+cd-da-bc is zero.