2/12+2/20+2/30+2/42+2/56+2/72+2/90=?1/3+1/15+1/35+1/63+1/99=
2/12+2/20+2/30+2/42+2/56+2/72+2/90=?1/3+1/15+1/35+1/63+1/99=
1+1/2+1/6+1/12+1/20+1/30+.+1/90 简便计算 2/3+2/15+2/35+2/63+2/99
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=多少
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=______
计算 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?(例:1/2=二分之一)
2\1+6\1+12\1+30\1+42\1+56\1+72\1+90\1+110\1= (提示:2\1=1-2\1.6
若a=1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110+1/132+1/
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+190+1/110=?
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+.1/9900=?
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/110+1/132=
2\1+6\1+12\1+20\1+30\1+42\1+56\1+72\1+90\1+110\1+132\1=?