8.9*0.2+8.8*0.2+8.7*0.2+.+8.1*0.2怎么简算,

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8.9*0.2+8.8*0.2+8.7*0.2+.+8.1*0.2怎么简算,
8.9*0.2+8.8*0.2+8.7*0.2+.+8.1*0.2怎么简算,

8.9*0.2+8.8*0.2+8.7*0.2+.+8.1*0.2怎么简算,
0.2×(8.9+8.8...+8.1)
=0.2×(8.9+8.1)×9÷2=15.3

=0.2*(8.9+8.8+...+8.1)=0.2*(8.9+8.1)*9/2=0.2*17*9/2=1.7*9=17-1.7=15.3

8.9*0.2+8.8*0.2+8.7*0.2+.....+8.1*0.2
=0.2x(8.9+8.8+8.7+...+8.1)
=0.2x[(8.9+8.1)+(8.2+8.8)+...+(8.4+8.6)+8.5+8.5-8.5]
=0.2x17x5-0.2x8.5
=0.2x5x17-1.7
=17-1.7
=15.3

=0.2*【8.9+8.1)+(8.8+8.2)+(8.7+8.3)+(8.6+8.4)+8.5】
=15.3