Quadratic equation KX ^ 2 + 2 (K + 1) x - (3K-1) = 0 if the sum of two elements in the equation is equal to the product, the value of K can be obtained

Quadratic equation KX ^ 2 + 2 (K + 1) x - (3K-1) = 0 if the sum of two elements in the equation is equal to the product, the value of K can be obtained

The relationship between two real number roots of bivariate quadratic equation: AX2 + BX + C = 0 (a ≠ 0), X1 + x2 = - B / A, X1 * x2 = C / A
x1+x2=-2(k+1)/k,x1*x2=-(3k-1)/k
-2(k+1)/k=-(3k-1)/k
The solution is k = 3

Solving quadratic equation
The square of X / [(2-x) (6-x) = 2.6
The square of X / [(2-x) (6-x)] = 2.6

x²/[(2-x）(6-x)]=2.6
5x²=13(2-x）(6-x)
5x²=13x²-104x+156
2x²-26x+39=0
x=(13±√91)/2

The vertex coordinates of the parabola y = x2-1 are______ ．

The vertex coordinates of parabola y = x2-1 are (0, - 1), so the answer is: (0, - 1)