What are the coordinates of the vertex for f(x) = 3x2 + 6x + 3? (−1, 0) (3, 6) (0, −1) (6, 3)

For
ax^2+bx+c=0
x value of vertex is -b/2a
y value is x value subsituted

3x^2+6x+3
a=3
b=6
-6/(2*3)=-6/6=-1

x coordinate is -1
plug it in
f(-1)=3(-1)^2+6(-1)+3
f(-1)=3(1)-6+3
f(-1)=0

the vertex is at (-1,0)