The axis of symmetry is x = 6
Further explanation
Discriminant of quadratic equation ( ax² + bx + c = 0 ) could be calculated by using :
D = b² - 4 a c
From the value of Discriminant , we know how many solutions the equation has by condition :
D < 0 → No Real Roots
D = 0 → One Real Root
D > 0 → Two Real Roots
Let us now tackle the problem!
An axis of symmetry of quadratic equation y = ax² + bx + c is :
\(\large {\boxed {x = \frac{-b}{2a} } }\)
Given:
\(f(x) = - (x + 9)(x - 21)\)
\(f(x) = - (x^2 - 21x + 9x - 189)\)
\(f(x) = - (x^2 - 12x - 189)\)
\(f(x) = -x^2 + 12x + 189\)
The axis of symmetry is
\(x = \frac{-b}{2a}\)
\(x = \frac{-12}{2(-1)}\)
\(x = \frac{-12}{-2}\)
\(\large {\boxed {x = 6} }\)
Learn more
- Solving Quadratic Equations by Factoring : https://brainly.com/question/12182022
- Determine the Discriminant : https://brainly.com/question/4600943
- Formula of Quadratic Equations : https://brainly.com/question/3776858
Answer details
Grade: High School
Subject: Mathematics
Chapter: Quadratic Equations
Keywords: Quadratic , Equation , Discriminant , Real , Number , Axis , Symmetry , Function
