✔ 最佳答案
The coefficient of x² term is 1.
The quadratic function that minimum y = 1 at x = 2 :
y = (x - 2)² + 1 ...... [1]
The above be function can be expressed as :
y = x² + bx + c ...... [2]
[2] = [1] :
x² + bx + c = (x - 2)² + 1
x² + bx + c = x² - 4x + 4 + 1
x² + bx + c = x² - 4x + 5
Compare the coefficients :
b = -4
c = 5