题干
观察下列等式：
第1个等式：x1=
=
(1−
) ；第2个等式：x2=
=
(
−
) ；
| 1 |
| 1 |
| × |
| 3 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 5 |
| × |
| 3 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 5 |
第3个等式：x3=
=
(
−
) ；第4个等式：x4=
=
(
−
) ；
| 1 |
| 5 |
| × |
| 7 |
| 1 |
| 2 |
| 1 |
| 5 |
| 1 |
| 7 |
| 1 |
| 9 |
| × |
| 7 |
| 1 |
| 2 |
| 1 |
| 7 |
| 1 |
| 9 |
则xl+x2+x3+…+x10=____．
