计算.(1+1.2+1.23+1.234)×(1.2+1.23+1.234+1.2345)-(1+1.2+1.23+1.234+1.2345)×(1.2+1.23+1.234)-数学

题目简介

计算.(1+1.2+1.23+1.234)×(1.2+1.23+1.234+1.2345)-(1+1.2+1.23+1.234+1.2345)×(1.2+1.23+1.234)-数学

题目详情

计算.
(1+1.2+1.23+1.234)×(1.2+1.23+1.234+1.2345)-(1+1.2+1.23+1.234+1.2345)×(1.2+1.23+1.234)
题型:解答题难度:中档来源:不详

答案

设1+1.2+1.23+1.234=a,1+1.2+1.23+1.234+1.2345=b,则:
(1+1.2+1.23+1.234)×(1.2+1.23+1.234+1.2345)-(1+1.2+1.23+1.234+1.2345)×(1.2+1.23+1.234),
=a×(b-1)-b×(a-1),
=ab-a-ab+b,
=b-a,
=(1+1.2+1.23+1.234+1.2345)-(1+1.2+1.23+1.234),
=1.2345.

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