高校问答i believe爱不离歌词:智力高手
来源：百度文库 编辑：高校问答 时间：2024/04/19 07:44:20
0.75x15+4.5x2.5, 3.6x31.4+43.9x6.4这2道题如何方便解
0.75x15+4.5x2.5
＝0.75x6x2.5+0.75x6x2.5
=0.75x6x2.5x2
=22.5
3.6x31.4+43.9x6.4
=3.6x31.4+(31.4+12.5)x6.4
=3.6x31.4+31.4x6.4+12.5x6.4
=31.4x10+12.5x6.4
=314+12.5x8x0.8
=314+100x0.8
=314+80
=394
0.75x15+4.5x2.5,
=7.5*1.5+4.5*2.5
=1.5*[7.5+3*2.5]
=1.5*15
=22.5
3.6x31.4+43.9x6.4
=[10-6.4]*31.4+43.9*6.4
=314-6.4*31.4+43.9*6.4
=314+6.4[43.9-31.4]
=314+6.4*12.5
=314+0.8*8*12.5
=314+0.8*100
=314+80
=394
第一题
4.5分为15乘0.3 0.3乘2.5是0.75
即: 2乘0.75乘15
0.75*15+4.5*2.5
=2.5*0.3*15+4.5*2.5
=4.5*2.5*2
=22.5