巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12
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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
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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](/uploads/image/z/2802731-59-1.jpg?t=%E5%B7%A7%E7%AE%97%EF%BC%9A%EF%BC%88100%2B12.3%2B23.4%EF%BC%89%C3%97%EF%BC%8812.3%2B23.4%2B34.5%EF%BC%89-%EF%BC%88100%2B12.3%2B23.4%2B34.5%EF%BC%89%C3%97%EF%BC%8812)
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
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
巧算:(100+12.3+23.4)×(12.3+23.4+34.5)-(100+12.3+23.4+34.5)×(12
计算123+234+345+456+567+678+789/12.3+23.4+34.5+45.6+56.7+67.8+
2.3+23.4+34.5+45.6+56.7+67.8+78.9巧算
23.4*(13.4-10)的简便运算
12.8×34.5+12.8×12.3+46.8×87.2
简便计算. 15.6789÷20÷5 2.8×23.4+11.1×57.6+6.54×28 34.5×8.23-34.5
简算:[23.4+15.4×(5+3/7)]×20%
12.8乘34.5加12.8乘12.3加46.8乘87.2=? 简便运算
12.8乘34.5加12.8乘12.3加46.8乘87.2简便
1、求:123+234+345+456+567+678+789—————————————————— 12.3+23.4+
一个数与23.4相乘后的积是(),把23.4增加10后,积就增加了5,原来的积是多少?
简便计算,(2分之1-8分之3)÷4分之3 23.4×18-23.4×81.25×5分之31+3.8÷5分之4 33.6