OG详解-OG3 数学2 Q7

The correct answer is 7. When an equation is of the form y = ax² + bx +c, where a, b, and c are constants, the value of y reaches its minimum when x =- b​2a​. Since the given equation is of the form y = ax² + bx +c, it follows that a =1, b =-14, and c = 22. Therefore, the value of y reaches its minimum when x=−（−14）2（1​）​ , or x=7.