At what value of x is the function y = x^{2} – 2x – 3 minimum?

A.
1 
B.
1 
C.
4 
D.
4
Correct Answer: Option A
Explanation
For y = ax^{2} – bx + c for minimum y
(frac{dy}{dx}) = 2x – 2
= (frac{dy}{dx}) = 0
∴ 2x – 2 = 0
x = 1
For y = ax^{2} – bx + c for minimum y
(frac{dy}{dx}) = 2x – 2
= (frac{dy}{dx}) = 0
∴ 2x – 2 = 0
x = 1