0.225×0.335+0.335×0.775+0.775×0.225 ＝（1-0.775）×0.335+0.335×0.775+0.775×0.225 ＝0.335 - 0.775×0.335 + 0.335×0.775+0.775×0.225 ＝0.335 ＋ 0.775×0.225 ＝0.509735
=0.335*(0.225+0.775)+0.775*0.225 =0.335+0.775*0.225
＝（1-0.775）×0.335+0.335×0.775+0.775×0.225 ＝0.335 - 0.775×0.335 + 0.335×0.775+0.775×0.225 ＝0.335 ＋ 0.775×0.225 ＝0.509375
原式＝.335(.225+.775)+.225*.775
=.335+.225(1-.225)
=.335+.225-.225^2
＝。56－。050625 【225平方＝22×23×100＋ 】
=.509375
将此题理解为: 0.225x0.335+0.335x0.775+0.775x0.225 =0.335x(0.225+0.775)+0.775x0.225) =0.335x1+0.225x(1-0.225) =0.335+0.225-0.225x0.225 =0.56-(0.5x0.45)x(0.5x0.45) =0.56-(2x0.5x0.45/2)x(2x0.5x0.45/2) =0.56-0.45x0.45/4 =0.56-0.2025/4 =0.56-0.050625 =0.509375
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