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For f(x) = 2x squared - 12x + 5, what is the equation of the axis of symmetry?
Ax = 3
Bx = 6
Cx = -3
Dx = 12
Answer & Solution
Correct answer: A. x = 3
1. The axis of symmetry of a quadratic in general form is the vertical line x equal to negative b over 2a.
2. Here a is 2 and b is negative 12.
3. So x equals 12 divided by 4, which is 3.
4. Forgetting to divide by 2a would give the wrong value 6.
_Source: OpenStax Precalculus (CC BY 4.0), section 3.2 Quadratic Functions_