重点题来了,（四道能简算的要简算）要写过程!快来速速答题,非尖子生1.1/2+1/6+1/12+1/20+1/30+1/42 2.31/42-(1/6+3/14) 3.9 3/4+99 3/4+999 3/4+9999 3/4 4.1/2+3/4+7/8+15/16+31/32+63/64
2019-06-27
重点题来了,（四道能简算的要简算）要写过程!快来速速答题,非尖子生
1.1/2+1/6+1/12+1/20+1/30+1/42
2.31/42-(1/6+3/14)
3.9 3/4+99 3/4+999 3/4+9999 3/4
4.1/2+3/4+7/8+15/16+31/32+63/64
优质解答
1/2+1/6+1/12+1/20+1/30+1/42
=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
1/2+1/6+1/12+1/20+1/30+1/42
=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