OG详解-OG8 数学1 Q20

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.