Mathematicians help me to solve the square root formula: X (n + 1) = xn + (A / xn &; xn) 1 / 2. What is the subscript of X on the left side of the equal sign

Mathematicians help me to solve the square root formula: X (n + 1) = xn + (A / xn &; xn) 1 / 2. What is the subscript of X on the left side of the equal sign

2xn=x(n-1)+y(n-1)
2yn=x(n+1)+y(n+1)
So y (n-1) = (xn + yn) / 2, substitute into Formula 1
We obtain 3XN = 2x (n-1) + yn
It can be obtained from equation 1
yn=2x(n+1)-xn
So 3XN = 2x (n-1) + 2x (n + 1) - xn
Let 2xn = x (n-1) + X (n + 1)
So xn is an arithmetic sequence
If Y1 = 2x2-x1, then x2 = (x1 + Y1) / 2
So the tolerance d = x2-x1 = (y1-x1) / 2
xn=x1+(n-1)d=x1+(n-1)(y1-x1)/2
yn=2x(n+1)-xn=x(n+2)=x1+(n+1)(y1-x1)/2
Note: it's OK not to have wealth