如题所述
第1个回答 2016-01-09
1.9×9.9＋0.19
=1.9×9.9+1.9×0.1
=1.9×（9.9+0.1）
=1.9×10
=19追问
=1.9×9.9+1.9×0.1
=1.9×（9.9+0.1）
=1.9×10
=19追问
1.2×2.5＋0.8×2.5怎么做
追答1.2×2.5＋0.8×2.5
=2.5×（1.2+0.8）
=2.5×2
=5
第2个回答 2016-01-09
追问
1.2×2.5＋0.8×2.5怎么做
追答