The vertex (- 2,1) of quadratic function passes through the point (2,1), and the analytic expression of quadratic function is obtained

The vertex (- 2,1) of quadratic function passes through the point (2,1), and the analytic expression of quadratic function is obtained

The title condition is wrong, should be through the point (2, - 1)
The solution consists of the vertex of quadratic function (- 2,1)
Let the quadratic function be y = a (x + 2) ^ 2 + 1
From the passing point (2, - 1)
Then a (2 + 2) ^ 2 + 1 = - 1
The solution is a = - 1 / 8
So the quadratic function is y = - 1 / 8 (x + 2) ^ 2 + 1
That is y = - 1 / 8x ^ 2-1 / 2x + 1 / 2