Respuesta :
Answer:
A)-18
Step-by-step explanation:
Given a quadratic equation of the form [tex]y=ax^2+bx+c[/tex], the axis of symmetry is determined by the formula [tex]x=-\frac{b}{2a}[/tex].
If the axis of symmetry of the equation: [tex]f(x)=3x^2+bx+4[/tex] is 3, then:
a=3, b=?, x=3
[tex]x=-\frac{b}{2a}\\3=-\frac{b}{2*3}\\b=-6X3=-18[/tex]
The correct option is A.
According to the vertex of the quadratic function, it is found that the value of b is b = -18.
What is the vertex of a quadratic equation?
A quadratic equation is modeled by:
[tex]y = ax^2 + bx + c[/tex]
The vertex is given by:
[tex](x_v, y_v)[/tex]
In which:
[tex]x_v = -\frac{b}{2a}[/tex]
[tex]y_v = -\frac{b^2 - 4ac}{4a}[/tex]
The axis of symmetry is [tex]x = x_v[/tex].
In this problem, the equation is:
f(x) = 3x² + bx + c.
The axis of symmetry is x = 3, hence:
[tex]-\frac{b}{2a} = 3[/tex]
[tex]-\frac{b}{6} = 3[/tex]
[tex]b = -18[/tex]
The value is of b = -18.
More can be learned about the vertex of a quadratic function at https://brainly.com/question/24737967
