Multiple choice

Consider the quadratic equation $f(x)=ax^{2}+bx+c$. Where $a, b, c\in R$ and $a\neq 0$ such that $f(x)=f(2-x)$ for all real number $x$. The sum of the roots of $f(x)$ is :

  1. $1$
  2. $2$
  3. $3$
  4. $4$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

f(x) = ax^2 + bx + c. f(x) = f(2-x) implies the axis of symmetry is x = 1. The vertex is at -b/2a = 1, so b = -2a. Sum of roots = -b/a = -(-2a)/a = 2.

AI explanation

The condition $f(x) = f(2-x)$ for all real numbers indicates that the quadratic function has a vertical axis of symmetry. The axis of symmetry for a parabola is located exactly halfway between its roots, meaning it can be found by taking the average of the roots. Setting the axis equation $x = (root 1 + root 2) / 2$ equal to the midpoint derived from the symmetry condition, we have $(root 1 + root 2) / 2 = (x + 2 - x) / 2$. Solving this simple equation shows the sum of the roots is 2.