题目内容
（2013?成都模拟）(1+
+
+
+
)×(
+
+
+
+
)-(1+
+
+
+
+
)×(
+
+
+
)．
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分析：如果按常规来做会很复杂，经过仔细观察，此题数字很有特点，于是设
+
+
+
+
=a，
+
+
+
=b，代入算式计算即可．
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解答：解：设
+
+
+
+
=a，
+
+
+
=b，则a-b=
+
+
+
+
-（
+
+
+
）=
，那么：
（1+
+
+
+
）×（
+
+
+
+
）-（1+
+
+
+
+
）×（
+
+
+
），
=（1+b）×a-（1+a）×b，
=a+ab-b-ab，
=a-b，
=
．
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（1+
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=（1+b）×a-（1+a）×b，
=a+ab-b-ab，
=a-b，
=
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点评：完成此题，采用设数法，计算较简便．
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