The first grade mathematics volume 1 of the people's Education Press

The first grade mathematics volume 1 of the people's Education Press

Title:
(1) How to draw down?
○●○○●○○○●
(2) Which line is different from the other three?
6 7 8 9 10
4 5 6 7 8
2 4 6 8 10
1 2 3 4 5

Mathematical problems about finding laws
one
-1/2 1/3
-1/4 1/5 -1/6
-1/7 1/8 -1/9 1/10
What's the second one on line 50?
-In which row and column is 1 / 1833?

The denominator of the first one in line 1 is 1 + 1 = 2
The denominator of the first one in line 2 is 2 + 1 + 1 = 4
The denominator of the first one in line 3 is 3 + 2 + 1 + 1 = 7
The denominator of the first one in line 4 is 4 + 3 + 2 + 1 + 1 = 11
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.
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The denominator of the first one in line 50 is 50 + 49 + 48 +... + 3 + 2 + 1 + 1 = 1276
According to the law of positive and negative numbers above
The second of line 50 should be 1 / 1277

The problem of finding the law in Mathematics
As shown in the figure, each square lattice is divided into two triangular lattices by a straight line. According to the information provided on the way, the law in the nth square lattice is expressed by the equation containing n
......
.....
...
1=1x1 1+3=2x2 3+6=3x3 .

1 = 1x1 can be written as 0 + 1 = 1x1, 1 + 3 = 2x2, 3 + 6 = 3X3, 6 + 10 = 4x4, 10 + 15 = 5x5,. [n (n-1)] / 2 + [n (n = 1)] / 2 = NxN
This is my answer

1+3=4
1+3+5=9
1+3+5+7=16
1+3+5+7+9=25
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After careful observation of the above operation and results, 1 + 3 + 5 + 7 +. + 2003 + 2005 + 2007 + 2009 = () is calculated, and the result is expressed by power

We can get the rule from the above. It is the last term plus 1 and then divided by 2 in the square. That is the square of (2009 + 1) / 2