0.7777×0.7+0.1111×2.1
=0.7777×0.7+0.1111×7×0.3
=0.7777×0.7+0.7777×0.3
=0.7777×(0.7+0.3)
=0.7777×1
=0.7777
0.7777×0.7+0.1111×2.1
=0.1111×(0.7×7)+0.1111×2.1
=0.1111×(4.9+2.1)
=0.1111×8
=0.8888
满意请采纳
0.7777×0.7+0.7777×0.3
=0.7777×(0.7+0.3)
=0.7777
0.7777×0.7+0.1111×0.3×7
=0.7777×(0.7+0.3)
=7.777
把2.1拆成7乘0.3