Unit number: 2, 4, 8, 6, 2, 4, ...
2, 4, 8, 6, one section, 20/4=5+0.
The number at the end of the twentieth power of 2 is 6.
The quadratic equation 1×3+ 1=4=2 is studied.
2×4+ 1=9=3 squared
3×5+ 1= 16=4 quadratic ...
Let n be a positive integer, please use the formula containing n to express the important step () of the above law.
1×( 1+2)+ 1=4=2^2
2×(2+2)+ 1=9=3^2
3×(3+2)+ 1= 16=4^2
……
n*(n+2)=(n+ 1)^2)