(2.15﹢5.17+3.62)×(5.17+2.15+8.5)-(3.62+2.15+8.5+5.17)×(2.15+5.17)用简便方法计算
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![(2.15﹢5.17+3.62)×(5.17+2.15+8.5)-(3.62+2.15+8.5+5.17)×(2.15+5.17)用简便方法计算](/uploads/image/z/204355-19-5.jpg?t=%282.15%EF%B9%A25.17%EF%BC%8B3.62%29%C3%97%285.17%EF%BC%8B2.15%EF%BC%8B8.5%29%EF%BC%8D%283.62%EF%BC%8B2.15%EF%BC%8B8.5%EF%BC%8B5.17%29%C3%97%282.15%EF%BC%8B5.17%29%E7%94%A8%E7%AE%80%E4%BE%BF%E6%96%B9%E6%B3%95%E8%AE%A1%E7%AE%97)
(2.15﹢5.17+3.62)×(5.17+2.15+8.5)-(3.62+2.15+8.5+5.17)×(2.15+5.17)用简便方法计算
(2.15﹢5.17+3.62)×(5.17+2.15+8.5)-(3.62+2.15+8.5+5.17)×(2.15+5.17)用简便方法计算
(2.15﹢5.17+3.62)×(5.17+2.15+8.5)-(3.62+2.15+8.5+5.17)×(2.15+5.17)用简便方法计算
原式=[(2.15+5.17)+3.62]×[(2.15+5.17)+8.5]-[3.62+8.5+(2.15+5.17)]×(2.15+5.17)
=(2.15+5.17)²+3.62×(2.15+5.17)+8.5×(2.15+5.17)+3.62×8.5-[3.62×(2.15+5.17)+8.5×(2.15+5.17)+(2.15+5.17)²]
=(2.15+5.17)²+3.62×(2.15+5.17)+8.5×(2.15+5.17)+3.62×8.5-3.62×(2.15+5.17)-8.5×(2.15+5.17)-(2.15+5.17)²
=3.62×8.5
=3.62×(9-0.5)
=3.62×9-3.62×0.5
=32.58-1.81
=30.77
或者:
令a=2.15+3.17
原式=(a+3.62)×(a+8.5)-(3.62+8.5+a)×a
=a²+3.62a+8.5a+3.62×8.5-(3.62a+8.5a+a²)
=a²+3.62a+8.5a+3.62×8.5-3.62a-8.5a-a²
=3.62×8.5
=3.62×(9-0.5)
=3.62×9-3.62×0.5
=32.58-1.81
=30.77