无上宗师
幼苗
共回答了22个问题采纳率:81.8% 举报
1.(1.3×3.9×11.7+3×9×27+1/17×3/17×9/17)/(1.3×2.6×3.9+3×6×9+1/17×2/17×3/17)
=[1.3×(1+3+9)+3×(1+3+9)+1/17 ×(1+3+9)]/[1.3×(1+2+3)+3×(1+2+3)+1/17 ×(1+2+3)]
=(1.3+3+1/17)(1+3+9)/(1.3+3+1/17)(1+2+3)
=(1+3+9)/(1+2+3)
=13/6
2.2/3+2/9+2/27+2/81+2/243
=2/243 ×(81+27+9+3+1)
=2/243 × 121
=242/243
4.2×3×4×5+5×6×7×8/2×3×4×5
=120+14
=134
5.(1+1/2+1/3+1/4)×(1/2+1/3+1/4+1/5)-(1+1/2+1/3+1/4+1/5)×(1/2+1/3+1/4)
设1/2+1/3+1/4=t
原式可化为
(1+t)(t+1/5)-(1+t+1/5)t
=1/5
1年前
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