设集合A={(x1,x2,x3,…,x10)|xi∈{﹣1,0,1},i=1,2,3,…,10},则集合A中满足条件“1≤|x1|+|x2|+|x3|+…+|x10|≤9”的元素个数为____
根之所以能够不断地伸长,是因为( )
2+23 =2 23 ,验证: 2+23 = 2×3+23 = 233 =2 23 ;
3+38 =3 38 ,验证: 3+38 = 3×8+38 = 338 =3 38