巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12.3+23.4)设:12.3+23.4=A(A+100)×(A+34.5)-(A+134.5)×A====

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巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12.3+23.4)设:12.3+23.4=A(A+100)×(A+34.5)-(A

巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12.3+23.4)设:12.3+23.4=A(A+100)×(A+34.5)-(A+134.5)×A====
巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12.3+23.4)
设:12.3+23.4=A
(A+100)×(A+34.5)-(A+134.5)×A
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巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12.3+23.4)设:12.3+23.4=A(A+100)×(A+34.5)-(A+134.5)×A====
巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12.3+23.4)
设:12.3+23.4=A =35.7
(A+100)×(A+34.5)-(A+134.5)×A
=A²+134.5A+100x34.5 - A²-134.5A
=100×34.5
=3450