The axis of symmetry for the graph of the function f (x) = 3x2 + bx + 4 is x = 3/2. What is the value of b?

The axis of symmety is the x value of the vertex

to find the x value of the vertex of ax^2+bx+c=0

x value=-b/2a

3x^2+bx+4=0

3/2=vertex

-b/2 (3) = 3/2

-b/6=3/2

times 6

-b=18/2

-b=9

times - 1

b=-9