1+3+5+7… +（2n-1）=______ (denoted by the formula containing N, where n = 1, 2, 3 ．）

1+3+5+7… +（2n-1）=______ (denoted by the formula containing N, where n = 1, 2, 3 ．）

The original formula is n × 1 + n (n − 1) 2 × 2 = N2, so the answer is: N2

1+3+5+7+9+...+(2n+1)+(2n-1)+(2n+3)
Explore the law: observe the pattern and formula composed of * below,
1 + 3 = 4 = 2, 1 + 3 + 5 = 9 = 3, 1 + 3 + 5 + 7 = 16 = 4
(1) Qing conjecture 1 + 3 + 5 + 7 + 9 +... + 19=___ ;
(2) Qing conjecture 1 + 3 + 5 + 7 + 9 +... + (2n-1) + (2n + 1) + (2n + 3)=____
(3) Please use the above rule to calculate: 103 + 105 + 107 +... + 2003 + 2005

1+3+5+7+9+...+(2n+1)+(2n-1)+(2n+3)
=[(1+2n+3)*(n+2)]/2=(n+2)^2
First question
1 + 3 + 5 + 7 + 9 +... + 19 = (8 + 2) ^ 2 = 100
Second question
1+3+5+7+9+...+(2n+1)+(2n-1)+(2n+3)
=[(1+2n+3)*(n+2)]/2=(n+2)^2
The third question
103+105+107+...+2003+2005.
=1+3+5+…… +2003+2005-（1+3+5+…… +101）
=（1001 +2)^2 -（49+2)^2
=1003^2 -51^2
=（1003-51）*（1003+51）
=1054*952
=1003408

1+3+5+7.+(2n+1)=______
Example: the power of 1 + 3 = 4 = 2
The second power of 1 + 3 + 5 = 9 = 3

1+3+5+7+.+(2n+1)=(n+1)²