颖颖兔
花朵
共回答了22个问题采纳率:95.5% 举报
1. 1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7
=1-1/7
=6/7 选D
2. 99999*99999+99999+100000
=99999*100000+100000
=100000*100000
=10000000000=10的10次方 选A
3. 5/12*(-2/7-5/7+1)
=5/12*0
=0 选D
1年前
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